Operating efficiency prediction of the dredger is an important basis to ensure engineering benefits. Regarding the difficulty in predicting the cutter suction dredger’s output，based on the theoretical model of specific cutting energy，this paper establishes a productivity prediction model of sand excavation by cutter suction dredger，determines the main influencing factors of sand excavation，and verifies results in combination with engineering cases. The results show that the standard penetration number is the key factor affecting the theoretical specific cutting energy. Through the mathematical model of sand standard penetration number and excavation productivity established by actual engineering，this paper better predicts the sand excavation productivity. The research results can guide and provide a reference for theoretical research on sand excavation by cutter suction dredger or on-site construction.