I know boiling point at vacuum is far below the room temperature. But I still wondering if the humidity reaches the saturated humidity (100% relative humidity), will the vapor condense to liquid, although it is probably going to evaporate again soon?
While dmckee points out your question is too vague, I'll take a shot and guess you're asking from a pop-sci standpoint. Since you mention vacuum chamber, I'm going to assume it's actively maintained. For example put a wet shirt in a vacuum chamber and pump it down.
The water will boil off but it has to be removed from the system because you are trying to maintain a vacuum. Thus the pump will condense the water (along with other gas molecules) outside of the chamber. By the time you get down to a good low vacuum pressure (< 1 mTorr) there will be no water or very few molecules left. Release the vacuum and your shirt will be dry.