In order to simulate the actual working condition of current energy generator, analyzes the operating principles of the DC motor and the hydraulic turbine, discusses their power and torque characteristics, and designs a double closed-loop control strategy for the control of current and speed of DC motor. Establishes simulation system of turbine by Matlab/Simulink and complete the system simulation tests under three typical working conditions of constant speed, slow growth rate and random flow rate. Experimental results show that the current and speed double closed-loop DC motor control system accurately simulates the main shaft torque of hydraulic turbine and meets the laboratory conditions for ocean current energy generator tests.