現在是持有正式綠卡，我返香港的話使唔使在美國呢邊搞手續先可以在香港入境？

hi, you can use ur HKID card or HK passport to enter HK. however u are holding a greencard, if you want to leave USA over 1 yr, you have to apply the re-entry permit before leaving USA, this re-entry permit gives u 2 yrs to stay outside USA. .... if u come back USA within 1 yr, there is nothing u have to do.
hope it can solve ur question.