Abstract: It is difficult to obtain accurate values of hydrodynamic parameters through wind tunnel test or numerical calculation, therefore, the system identification method is usually employed for an aircraft to optimize its fluid parameters. However, the identification method for aircraft uses square-wave open-loop input, which is destructive and dangerous to a certain extent, so it is difficult to be used in undersea vehicle parameter identification. In this paper, a closed-loop control method adopting alternate path points is proposed to replace the traditional square-wave open-loop input for undersea vehicle in sea trial. It can both fully inspire undersea vehicle’s dynamic characteristics and ensure the safety of navigation. In order to reduce the difficulty of identification, the undersea vehicle is divided into several channels. Then, a certain type of undersea vehicle is taken as an example to optimize the parameter identification. The results show that satisfactory identification results of the channel can be obtained in sea trial as long as the actuator keeps the limit rudder for a period of time, and single channel parameter identification can also obtain high identification precision. After parameter identification, the open-loop simulation results are consistent with that from sea trial, which proves the feasibility of the proposed method in practical engineering application.