diff --git a/ooxml/XWPF/Usermodel/XWPFAbstractNum.cs b/ooxml/XWPF/Usermodel/XWPFAbstractNum.cs
index 1b658ce46..070960429 100644
--- a/ooxml/XWPF/Usermodel/XWPFAbstractNum.cs
+++ b/ooxml/XWPF/Usermodel/XWPFAbstractNum.cs
@@ -31,7 +31,7 @@ public class XWPFAbstractNum
         private CT_AbstractNum ctAbstractNum;
         protected XWPFNumbering numbering;
 
-        protected XWPFAbstractNum()
+        internal XWPFAbstractNum()
         {
             this.ctAbstractNum = null;
             this.numbering = null;
@@ -116,6 +116,11 @@ internal void SetLevelTentative(int lvl, bool tentative)
             else
                 this.ctAbstractNum.lvl[lvl].tentative = ST_OnOff.off;
         }
+
+        internal void SetCTAbstractNum(CT_AbstractNum ctAbstractNum)
+        {
+            this.ctAbstractNum=ctAbstractNum;
+        }
     }
     /// <summary>
     /// Numbering Definition Type
diff --git a/ooxml/XWPF/Usermodel/XWPFNumbering.cs b/ooxml/XWPF/Usermodel/XWPFNumbering.cs
index 64516f476..5877da2f1 100644
--- a/ooxml/XWPF/Usermodel/XWPFNumbering.cs
+++ b/ooxml/XWPF/Usermodel/XWPFNumbering.cs
@@ -230,6 +230,14 @@ public XWPFAbstractNum GetAbstractNum(string abstractNumID){
             }
             return null;
         }
+        public List<XWPFAbstractNum> GetAbstractNums()
+        {
+            return abstractNums;
+        }   
+        public List<XWPFNum> GetNums()
+        {
+            return nums;
+        }
         /**
          * Compare AbstractNum with abstractNums of this numbering document.
          * If the content of abstractNum Equals with an abstractNum of the List in numbering
@@ -273,13 +281,22 @@ public string AddAbstractNum(XWPFAbstractNum abstractNum)
             }
             else
             {
-                ctNumbering.AddNewAbstractNum();
-                abstractNum.GetAbstractNum().abstractNumId = pos.ToString();
+                abstractNum.SetCTAbstractNum(ctNumbering.AddNewAbstractNum());
+                abstractNum.GetAbstractNum().abstractNumId = FindNextAbstractNumberingId().ToString();
                 ctNumbering.SetAbstractNumArray(pos, abstractNum.GetAbstractNum());
             }
             abstractNums.Add(abstractNum);
             return abstractNum.GetAbstractNum().abstractNumId;
         }
+        private long FindNextAbstractNumberingId()
+        {
+            long maxId = 0;
+            foreach(XWPFAbstractNum num in abstractNums)
+            {
+                maxId = Math.Max(maxId, long.Parse(num.GetAbstractNum().abstractNumId));
+            }
+            return maxId + 1;
+        }
         /// <summary>
         /// Add a new AbstractNum
         /// </summary>
diff --git a/testcases/ooxml/XWPF/UserModel/TestXWPFNumbering.cs b/testcases/ooxml/XWPF/UserModel/TestXWPFNumbering.cs
index 8498bfc4b..8a8824cdd 100644
--- a/testcases/ooxml/XWPF/UserModel/TestXWPFNumbering.cs
+++ b/testcases/ooxml/XWPF/UserModel/TestXWPFNumbering.cs
@@ -21,6 +21,8 @@ namespace TestCases.XWPF.UserModel
     using NPOI.OpenXmlFormats.Wordprocessing;
     using NPOI.XWPF.UserModel;
     using NUnit.Framework;using NUnit.Framework.Legacy;
+    using System;
+    using System.Linq;
 
     [TestFixture]
     public class TestXWPFNumbering
@@ -110,6 +112,56 @@ public void TestOverrideList()
             CT_NumLvl ctNumLvl = ctNum.GetLvlOverrideArray(0);
             ClassicAssert.AreEqual("upperLetter", ctNumLvl.lvl.numFmt.val.ToString());
         }
+        [Test]
+        public void TestAddAbstractNum()
+        {
+            using(XWPFDocument doc = XWPFTestDataSamples.OpenSampleDocument("NumberingWithOutOfOrderId.docx"))
+            {
+                doc.GetNumbering().AddAbstractNum(new XWPFAbstractNum());
+                var count = doc.GetNumbering()
+                    .GetAbstractNums().Select(e=>Int32.Parse(e.GetCTAbstractNum().abstractNumId)).Distinct().Count();
+                ClassicAssert.AreEqual(doc.GetNumbering().GetAbstractNums().Count, count);
+            }
+        }
+        [Test]
+        public void testAddAbstractNumIfAbstractNumNotEqualNull()
+        {
+            string abstractNumId = "1";
+            XWPFDocument docOut = new XWPFDocument();
+            XWPFNumbering numbering = docOut.CreateNumbering();
+
+            var cTAbstractNum = new CT_AbstractNum();
+            // must set the AbstractNumId, Otherwise fail
+            cTAbstractNum.abstractNumId = abstractNumId;
+            XWPFAbstractNum abstractNum = new XWPFAbstractNum(cTAbstractNum);
+            abstractNumId = numbering.AddAbstractNum(abstractNum);
+            var numId = numbering.AddNum(abstractNumId);
+
+            XWPFDocument docIn = XWPFTestDataSamples.WriteOutAndReadBack(docOut);
 
+            numbering = docIn.GetNumbering();
+            XWPFNum num = numbering.GetNum(numId);
+            var compareAbstractNum = num.GetCTNum().abstractNumId.val;
+            ClassicAssert.AreEqual(abstractNumId, compareAbstractNum);
+        }
+
+        [Test]
+        public void testAddAbstractNumIfAbstractNumEqualNull()
+        {
+            XWPFDocument docOut = new XWPFDocument();
+            XWPFNumbering numbering = docOut.CreateNumbering();
+
+            XWPFAbstractNum abstractNum = new XWPFAbstractNum();
+            var abstractNumId = numbering.AddAbstractNum(abstractNum);
+            var numId = numbering.AddNum(abstractNumId);
+
+            XWPFDocument docIn = XWPFTestDataSamples.WriteOutAndReadBack(docOut);
+
+            numbering = docIn.GetNumbering();
+            XWPFNum num = numbering.GetNum(numId);
+
+            var compareAbstractNum = num.GetCTNum().abstractNumId.val;
+            ClassicAssert.AreEqual(abstractNumId, compareAbstractNum);
+        }
     }
 }
diff --git a/testcases/test-data/document/NumberingWithOutOfOrderId.docx b/testcases/test-data/document/NumberingWithOutOfOrderId.docx
new file mode 100644
index 000000000..6c471c43b
Binary files /dev/null and b/testcases/test-data/document/NumberingWithOutOfOrderId.docx differ