Hydraulic drive system is widely used in propel system and working device of skid steer loader，the main control valve integrates pilot oil overflow valve,relief valve,pressure compensation valve,shuttle valve and throttle element.The hydraulic diagram and working principle of a certain type of skid steer loader were introduced,it was pointed out that arm and bucket were in failures of vibration while worked,then the possible causes to vibration fault were analyzed for troubleshooting.A solution to solve this kind of problem was presented,that was increasing throttle on the outside circuit of the pressure compensation valve orifice to produce delay in the feedback channel,thus the phase of the feedback signal was changed.The results show that after implementing the improvement plan on the slide loader,vibration of movable arm and bucket under various conditions has been eliminated,the pressure and flow of the hydraulic system are stable and vibration is eliminated.