The navigation characteristics of ships in intermediate channels are closely related to the navigation efficiency of navigable buildings and the safety of ship navigation.A scale test of tugboat model is used to study the navigation characteristics of the ship in the middle channel of the navigable building of the Goupitan Hydropower Station，and the sinking amount characteristics of the ship under different sailing speeds are analyzed.The relationship between the maximum sinking amount of the ship in the intermediate channel and the sailing speed，underwater area of channel，area below the water surface of midship section of ship and initial water depth is established，and a dimensionless formula that can accurately predict the maximum sinking amount of the ship is established.The research results show that：1) Under the same speed，the sinking amount of the ship out of the cabin is much larger than that of the entering cabin，and the ships exit process is the control condition of the ships sinking amount.2) When the section coefficient of the intermediate channel is less than 3.0，the change in section coefficient has a more significant impact on the sinking amount of ships ，and the smaller the section coefficient，the more significant the impact on the sinking volume of ships；when the section coefficient of the intermediate channel is greater than 4.0，the influence of the increase of the section coefficient on the sinking volume of the ship decreases rapidly.