The relevant introduction development of the micro electromechanical systems (MEMS) is carried out in this paper. The pressure sensor is an important component of micro electromechanical systems (MEMS). Many aspects of the pressure sensor are studied，simulated and analyzed by us. The principle of work of the pressure sensor is elaborated in details and the material selection is studied also. The correlative performance indexes, such as precision and the repeatability of pressure sensor, are explored. In the following part of this paper, through the finite element simulation software, the analytic study of some performance parameters of the sensor chip is carried out in detail. Through the analysis, we find that the sensor designed here has many advantages.