Abstract: A highly reliable and lowcost solution was put forward to solve the poor precision problem of the conventional equaldisplacement pump controlled synchronous circuit. An oil spill branch， made of a highspeed onoff valve， was added on each pump’s pressure pipeline of the conventional circuit. By using the PWM (pulse width modulation) method to control each highspeed onoff valve， highprecision multicylinder synchronization was realized. Detailed hydraulic principle diagram and the synchronization control method were presented as well. The scheme has been used in a twocylinder synchronous system of a mill entranceguide device for nearly one year， with the synchronous absolute error being kept under 15mm. The practical results showed that the scheme is worth promoting for its simplicity and practicality.

Key words: high speed onoff valve, pump controlled synchronization, hydraulic synchronization, synchronization control, pulse width modulation