VSTO

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using Excel = Microsoft.Office.Interop.Excel;
using Office = Microsoft.Office.Core;
using Microsoft.Office.Tools.Excel;
namespace VSTO
{
    public partial class ThisAddIn
    {
        private void ThisAddIn_Startup(object sender, System.EventArgs e)
        {
           //Instantiate the Application object
            Excel.Application ExcelApp = Application;
            //Add a Workbook
            Excel.Workbook workbook = ExcelApp.Workbooks.Add();
            //Get the First sheet
            Excel.Worksheet sheet = (Excel.Worksheet)workbook.Sheets["Sheet1"];
            //Merge A1-B5 to one cell
            sheet.get_Range("A1", "B5").Merge();
            //Save the file
            workbook.SaveAs("MergedCells.xlsx");
        }
        private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
        {
        }
        #region VSTO generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InternalStartup()
        {
            this.Startup += new System.EventHandler(ThisAddIn_Startup);
            this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
        }
        #endregion
    }
}

Spire.XLS

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Spire.Xls;
 
namespace Spire.XLS
{
    class Program
    {
        static void Main(string[] args)
        {
            //Initialize a new instance of workbook
            Workbook workbook = new Workbook();
 
            //Get the first worksheet
            Worksheet sheet = workbook.Worksheets[0];
 
            //Merge A1-B5 to one cell
            sheet.Range["A1:B5"].Merge();
         
            //Save and Launch
            workbook.SaveToFile("MergedCells.xlsx", ExcelVersion.Version2010);
            System.Diagnostics.Process.Start("MergedCells.xlsx");
 

        }
    }

}

慧都控件網