Another question is i will be arrive at baiyun airport at midnight

Thanks Crystal for the useful answer.
Another question is i will be arrive at baiyun airport at midnight instead of taxi/cab can i use train/subway? What is the operating hours for that at the baiyun airport? If using taxi how much the charges? I will stay at louidin mega apartment hotel(around beijing road at yuexie district).
This is for my budget group tour.thanks for your help.