The function of locking circuit for press machine is to keep actuators staying in the original position accurately, even though leakage or other external factors occur when actuators do not work. By locking circuit, the pressure-holding effect，anti-leakage and the stability of load cylinder piston were guaranteed, which ensures the normal operation of machine. For three kinds of locking circuit of press including reversing valve, double hydraulic controlled check valve and balance valve lock circuit，their working principles were analyzed，and the simulations of the above locking circuits were conducted by AMESim, Furthermore, the experiment was conducted on hydraulic test bench. The results show that the displacement curve of hydraulic cylinder obtained by the simulation is in agreement with that of the actual experiment，which verifies the correctness of the simulation.