https://www.hocexcel.online/huong-dan-gop-nhieu-file-excel-thanh-1-file.html

MergeExcelFiles.bas

Sub MergeExcelFiles()
    Dim FilesToOpen
    Dim x As Integer
    Dim wb As Workbook
    Dim nrow As Long

    On Error GoTo ErrHandler
    Application.ScreenUpdating = False

    FilesToOpen = Application.GetOpenFilename _
      (FileFilter:="Microsoft Excel Files (*.xlsx), *.xlsx", MultiSelect:=True, Title:="Files to Merge")

    If TypeName(FilesToOpen) = "Boolean" Then
        MsgBox "No Files were selected"
        GoTo ExitHandler
    End If

    x = 1
    While x <= UBound(FilesToOpen)
        Set wb = Workbooks.Open(Filename:=FilesToOpen(x))
        
        If x = 1 Then
            wb.Sheets(1).UsedRange.Copy ThisWorkbook.Sheets(1).Range("A1")
        Else
            lr = ThisWorkbook.Sheets(1).UsedRange.Rows.Count
            wb.Sheets(1).UsedRange.Offset(1).Copy ThisWorkbook.Sheets(1).Range("A" & lr + 1)
        End If
        
        wb.Close False
        x = x + 1
    Wend

ExitHandler:
    Application.ScreenUpdating = True
    Exit Sub

ErrHandler:
    MsgBox Err.Description
    Resume ExitHandler
End Sub