Based on the structural and dynamic method, this paper sets up a dynamic model on the traffic capacity of the TGP ship lock to obtian the potential capacity, which describes the dynamic relationship between the cargo-boat tonnage, operating time, ship number, efficiency of using area with traffic capacity. The paper also calculates the traffic capacity of the TGP ship lock from 2011 to 2030, and forecasts that the traffic capacity of the TGP ship lock will be saturated after 2015, and advices to optimize the standard ships and start research and demonstration on the newly-built navigation facilities.