Since the trial operation of the Three Gorges ship lift,the unstable working state of the accurate parking system makes that the ship lift chamber cannot accurately stop on the upper part and the downstream water level occasionally.In order to improve the working performance of the Three Gorges accurate parking system,we calculate and analyze its detection accuracy both in the dynamic and nonstatic condition,and put forward the improvement plan based on the theoretical analysis and experimental data.The results show that the improvement plan of pluse width modulation(PMV) regulation and adjustments of the voltage and speed,can increase the sensitivity of the float that manifest the water level,which can satisfy the requirements of stable operation of Three Gorges ship lift at the present stage.