With the progress of science and technology, many countries have studied the optimization of ship propulsion system and made in-depth exploration of frequency conversion debugging technology. In this paper, the advantages of frequency conversion debugging technology are given, the type of frequency converter is selected, and the ship propulsion system is designed. In the simulation of speed and load torque at different times in the direct torque test, the load torque of the motor is 600 N·m when the simulation starts, and suddenly increases to 1300 N·m after 10 s. At the 15th, the speed is 750 rpm and the load torque is 1100 N·m. The frequency conversion debugging technology can obviously adjust the ship speed. This paper highlights the advantages of the frequency conversion debugging technology.