Vacuum humidifying machine is an important mainframe in the line of the production of smoke shell. It is very important of improving the quality of tobacco and raising the profits of cigarette factories to control effectively the process of manufacture and production parameters. For the problem of control system on vacuum humidifying machine, the method of adopting computer direct control is put forward and its software is developed on windows platform. The software makes course control automatic thoroughly and viewable, providing users a friendly interface which can make it convenient to adjust manufacture engineering and parameters according to actual situation. The software of the control system and its design are described in detail in this paper.