Sub UnmergeAndFill()
    Dim ws As Worksheet
    Dim rng As Range
    Dim mergedRange As Range
    Dim cellValue As Variant
    
    ' 设置为当前活动工作表
    Set ws = ActiveSheet
    
    ' 遍历工作表中的所有单元格
    For Each rng In ws.UsedRange
        ' 检查是否是合并单元格
        If rng.MergeCells Then
            ' 获取合并区域
            Set mergedRange = rng.MergeArea
            ' 获取合并区域的第一个单元格的值
            cellValue = mergedRange.Cells(1, 1).Value
            ' 取消合并
            mergedRange.UnMerge
            ' 将值填充到整个原来合并的区域
            mergedRange.Value = cellValue
        End If
    Next rng
    
    MsgBox "合并单元格已取消并填充完成！", vbInformation
End Sub