请问如何编写代码才能使得ＶＢ的文本框只能输入大小字母

在KeyPress里判断一下KeyAscii就行

条件是什么啊，不懂啊

你学过C,不知道大写字母的Ascii码么?

用Ucase()

Private Sub Text_KeyPress(KeyAscii As Integer)
If (KeyAscii >=Asc("a") and KeyAscii <= Asc("z")) or (KeyAscii >= Asc("A") and KeyAscii <=Asc("Z")) Then
KeyAscii = KeyAscii
else
KeyAscii=0
End If
End Sub

顺便说下如果想用退格删除可以加上 or KeyAscii = 8