A kind of digital pressure control project is put forward to solve the problem of pressure fluctuation inside the carriage by using the experience of airplane's pressure control system. Based on the pressure difference monitored between the inside and outside of the carriage, the control signal is output to the actuator by the controller, according to the control program set in it, in order to stabilize the pressure in the carriage. After the mathematical models of the main parts of the control system are found, a mathematical model of the whole system is established. Fuzzy control technology is applied in the new control system. The fuzzy controller is designed by using the matlab software, and then the simulation system is constructed. It is proved practical by the simulation result.