A numerical geometry model for the inlet of the Three Gorges Project lock was set up. According to the hydraulic characteristics of inlet flow possessing the free surface of inlet flow and the larger curved wall, the numerical model and the grid borders conditions were established. The motions of the inlet flow were calculated under the conditions of the water levels of 145.0 m and 175.0 m respectively. The numerical results are in good agreement with the data of physical model and prototype. Therefore, the numerical model was effective to study the hydraulic characteristics of the flow conditions in the upstream approach channel and water delivery gallerys.