The underwater robot based on artificial intelligence requires small size, stable motion, and its control system requires low power consumption, reliable performance, and easy operation. This article uses STM32F407 as the main control unit to build the underwater robot motion control system and designs the software structure and data collection process for the entire system. The thruster is tested for data, and the ROV spatial motion coordinate system is established. Then, in response to the characteristics of multiple control nodes, large communication volume, and strong real-time performance of the flexible long fin biomimetic thruster, the internal communication network of the control system was established using a field bus. Finally, the details of the software and hardware implementation of the control system were introduced. The experimental results showed that the control system had good control performance.