The synchronous control system is the essential device to the giant forging hydraulic press whose synchronization control performance quality will directly determine the quality of the product. Through establishing the synchronization control system mathematical model, simulation experiments of the influence factors were carried out and the results show that owing to the hydraulic system of nonlinear, time-variant and mutual function between channels, various channel‘s parameters can not be achieved exactly the same, which causes the synchronization error that is produced by the system itself inherent characteristic difference.