试试
Dim Book As New XLS.Book(路径1)
Dim Sheet As XLS.Sheet = Book.Sheets(0)
Dim dict As New Dictionary(Of String, Double)
For n As Integer = 0 To Sheet.Rows.Count - 1
dict.Add(sheet(n, 1).VALUE, sheet(n, 2).VALUE)
Next
For Each dr3 As DataRow In DataTables("表A").Select("编码 is not null ")
If dict.ContainsKey( dr3("编码")) Then
dr3("单价") = dict( dr3("编码"))
End If
Next