In order to simulate the high pressure environment in deep-sea, a set of tester which can simulate the deep-sea environment was designed. Based on the analysis of its control system, this paper proposed a closed-loop control strategy of pressure. Hardware circuit of the constant frequency variable speed control system was designed. Its main control circuit used Atema8L, a single-chip microcomputer, as the core. ECN30206 was used in the drive circuit as the core and Max7219 was used in the show circuit as the core. Then software was made. The various parts of the hardware circuit can be individually used to meet different needs. And they can also form a closed-loop control system. This system not only can improve the accuracy of pressure adjustment significantly, but also have energy-saving effect.