My Flight is arrive at Baiyun Airport on 10.40 pm. Can I use Subway to go Haizhu Square .

The local subway line 3 connects the airport south and the city proper.
If you want to go to the Haizhu Square, you need to take the line 3 to Jiahewanggang Station and then change to line 2 to Haizhu Square.
The last train of the line 3 from the airport is at 23:00 and the last train of line 2 from Jiahewanggang 23:15, so I do not think the time is enough for you to catch the last train from Jiahewanggang.

In my opinion, you can take the airport shuttle bus line 5 to the Haizhu Square directly. It would still be in service upon your landing!

Thank you very much for the answer . That is very kind of you.