It introduces the structure form and working principle of a pitching hydraulic system for a closed tank. A static charge method of the tank was illustrated, and performance tests were carried out using a manual operation and the motor driving conditions separately.The results show that the system is operating normally, steady in state, the oil pressure fluctuation within the closed tank during each cycle is very small, and the temperature is relatively stable along with chinge in time. It is able to meet the requirements in application.