Aiming at the construction scale of Paihe second-line ship lock in the Yangtze-to-Huaihe water diversion project，according to the ship characteristics in engineering construction area，the ship lock passing capacity indexes of different chamber dimension schemes are calculated by using the stochastic simulation method of ship arrangement. In combination with the adaptability factors of chamber dimension schemes to ship combinations，the design schemes of chamber dimension are initially selected. Furthermore，comparative analysis is carried out from the perspectives of ship lock construction site conditions，passing capacity requirements，ship type adaptability and operation scheduling strategy，to comprehensively demonstrate the ship lock construction scale.