Abstract: In closed-loop control systems, there is a backlash usually in a mechanical transmission devices.Hence dynamic qualities of the system are becoming worse, sometimes an autonomous oscillation will occur and the system will be unstable.Obviously , the better way is to make the backlash as small as possible. However improving the precision of mechanical manufacturing and installing is limited. It is practically impossible to eliminate backlash entirely. This papr presents a compensation method using a linear phase lead network. The results of calculation and simulation coincide with the test well.The aero-engine ground test with the digital speed control system has shown that this method is able to make the engine work stably and the autonomous ocillation excited by the backlash has gone.