The lock capacity is one of the core concerns for the Pinglu Canal. This paper analyzes the factors influencing the lock capacity. Through computer simulation，three main indicators，i.e. the average total tonnages per lockage，the average vessel number per lockage，and the occupancy rate of the lock chamber，are acquired，and according to which，the lock capacities of the two operation modes including separate operation of large and small locks with a reasonable scale and random operation of the double-lane lock are compared. Moreover，the lock capacity and ship’s freight tonnage under the separate operation mode are adjusted. The result shows that double-lane locks shall be built at the same time，the separate mode provides a bigger capacity when the 1 000 DWT vessel accounts for a larger proportion，and some 1 000 DWT vessels have to pass through the big lock to ensure that the small lock’s capacity meets the transport demand.