If (Worksheets("Sheet1").Range("D2").Select = True) Then
MsgBox "You reach D2"

End If


It 's doesn't work correctly. Because when I run this, it is checking, the program select the cell D2, then give out message. It is incorrect.

How can I make a checking function?

Try this:
Sub checkA()
If (ActiveCell.Address(False, False) = "D2") Then
MsgBox "You reach D2"
Else
MsgBox "You are at " & ActiveCell.Address & ""
End If

End Sub