With the rapid development of economic and social society, China has initially established urban subway network， however, due to various factors, the existing subway network is not perfect, and there are a series of problems in the process of subway operation. Therefore, in order to solve these important problems, the metro management department has analyzed the metro environmental control system and found that there are huge defects in the linkage control of the fan and the air valve. In this paper, the linkage control mode of fan valve in metro environmental control system is studied.