The electrohydraulic proportional position synchronization control system of hydraulic cylinder is affected by its own and external disturbances, which results in the asynchronization of cylinder positions on both sides. In order to solve this problem, the mathematical model of the electrohydraulic proportional control system of hydraulic cylinder was established based on the test platform of synchronous control of cylinder positions on both sides. Based on the defects of equal mode and masterslave mode in engineering application, the “equal + masterslave” control mode was adopted. The active disturbance rejection controller(ADRC) was designed and the simulation model of the synchronous ADRC of cylinder positions on both sides were built for simulation research, and the simulation results were compared with those of traditional PID control. The results show that the by using the ADRC the response speed and antidisturbance ability of the system can be improved more effectively, and the synchronization error of the system is reduced.