Microsoft.Office.Interop.Word.Application winword = new Microsoft.Office.Interop.Word.Application();

            //Set animation status for word application  
            winword.ShowAnimation = false;

            //Set status for word application is to be visible or not.  
            winword.Visible = false;

            //Create a missing variable for missing value  
            object missing = System.Reflection.Missing.Value;

            //Create a new document  
            Microsoft.Office.Interop.Word.Document document = winword.Documents.Add(ref missing, ref missing, ref missing, ref missing);
                       

            //adding text to document  
            document.Content.SetRange(0, 0);
            document.Content.Text = "This is test document ";

            //Add paragraph with Heading 1 style  
            Microsoft.Office.Interop.Word.Paragraph para1 = document.Content.Paragraphs.Add(ref missing);
            object styleHeading1 = "Heading 1";
            para1.Range.set_Style(ref styleHeading1);
            para1.Range.Text = "Para 1 text";
            para1.Range.InsertParagraphAfter();

            string htmlFile = @"C:\Users\admin\Desktop\Temp_3.htm";
            para1.Range.InsertFile(htmlFile, System.Type.Missing, System.Type.Missing, System.Type.Missing, false);
            
            //Save the document  
            object filename = @"C:\Users\admin\Desktop\temp.docx";
            document.SaveAs2(ref filename);
            document.Close(ref missing, ref missing, ref missing);
            document = null;
            winword.Quit(ref missing, ref missing, ref missing);
            winword = null;
            Console.Read();