The planning lock capacity of ship lock is an important basis for determining the scale and standard of the lock construction.Because of the large deviation between the three key parameters such as ship type,ship water level difference and cargo flow in the lock design stage,there is a large deviation from the actual situation,which leads to a serious deviation from the forecast result and thus affects the accuracy of the scale and layout of the lock.Taking the actual operation data of a ship lock in Jiangsu Province for example,we analyze and compare the difference between the above-mentioned three parameters in the planning and actual operation stage using the capacity calculation method recommended by the lock design specification,and make a conformance checking of the berthing conditions.The results show that the lock design parameters have great influences on the analysis of the lock capacity,and the result of lock capacity calculated by combing the ship standard and water level is seriously conservative.In order to improve the accuracy of the planning for the lock capacity,further analysis and demonstration shall be carried out to the ship type and water level combination.