遍历所有sheet,比如
Dim Book As New XLS.Book("c:\reports\test.xls")
Dim lst As New List(Of String)
For Each sheet As XLS.Sheet In Book.Sheets
lst.Add(sheet.Name & "$")
Next
For Each s As String In lst
Dim mg As New Merger
mg.SourcePath = "c:\reports\test.xls"
mg.Format = "excel" '指定格式
mg.SourceTableName = s '指定要合并的表
mg.DataTableName = "订单" '指定接收数据的表
mg.Merge() '开始合并
Next