'tuanchung1997@gmail.com
Sub MergeExcelFiles()
    Dim fnameList, fnameCurFile As Variant
    Dim countFiles, countSheets As Integer
    Dim wksCurSheet As Worksheet
    Dim wbkCurBook, wbkSrcBook As Workbook
 
    fnameList = Application.GetOpenFilename(FileFilter:="Microsoft Excel Workbooks (*.xls;*.xlsx;*.xlsm),*.xls;*.xlsx;*.xlsm", Title:="Choose Excel files to merge", MultiSelect:=True)
 
    If (vbBoolean <> VarType(fnameList)) Then
 
        If (UBound(fnameList) > 0) Then
            countFiles = 0
            countSheets = 0
 
            Application.ScreenUpdating = False
            Application.Calculation = xlCalculationManual
 
            Set wbkCurBook = ActiveWorkbook
 
            For Each fnameCurFile In fnameList
                countFiles = countFiles + 1
 
                Set wbkSrcBook = Workbooks.Open(Filename:=fnameCurFile)
 
                For Each wksCurSheet In wbkSrcBook.Sheets
                    countSheets = countSheets + 1
                    wksCurSheet.Copy after:=wbkCurBook.Sheets(wbkCurBook.Sheets.Count)
                Next
 
                wbkSrcBook.Close SaveChanges:=False
 
            Next
 
            Application.ScreenUpdating = True
            Application.Calculation = xlCalculationAutomatic
 
            MsgBox "Processed " & countFiles & " files" & vbCrLf & "Merged " & countSheets & " worksheets", Title:="Merge Excel files"
        End If
 
    Else
        MsgBox "No files selected", Title:="Merge Excel files"
    End If
End Sub