The invention relates to a pressure load simulating system suitable for a deep-sea equipment hydraulic system and application thereof, and belongs to the technical field of marine equipment detecting.The system comprises a piston hydraulic cylinder, a three-position four-way switching valve, a working pressure meter, a working pressure transmitter, a rapid switching joint, a working pressure regulating valve, a controller, a filtering device, a first motor, a first hydraulic pump, a first one-way valve, an energy accumulator, an unloading valve, a throttle valve, an input pressure transmitter, an input pressure meter and a piston displacement sensor; the controller is electrically connected with the working pressure adjusting valve, the unloading valve, the input pressure transmitter, thepiston displacement sensor and the working pressure transmitter. The system can be applied to the detection of the deep-sea equipment hydraulic system and suitable for the load simulation of the deep-sea equipment hydraulic system which acquires power depending on volume variation, non-linear regulations of sea water pressure along with sea water depth can be simulated, and the simulation is closer to the real condition of the sea.