Aiming at the operation automation and high-precision safety operation requirements of trailer-type large-load special vehicles, a set of trailer-type unit autonomous navigation control system was designed for the large-load tractor. The vehicle-mounted program control system adopted a modular distributed system, and the communication between the modules in the system was realized through the CAN bus. The TCP protocol was used for data communication between the remote operation and management platform and the vehicle-mounted program control terminal, so as to realize the information exchange between the remote operation and management platform and the vehicle-mounted program control system. The kinematic model of the trailer-type special vehicle was established, and the towing state and the minimum turning radius of the towed machine were analyzed during the towing operation. Aiming at the defect of fixed foresight distance in the traditional pure pursuit algorithm, the foresight distance was dynamically calculated based on the current realtime speed of the tractor, tracking path curvature, heading and other information, and the fixed foresight distance into dynamic foresight distance tracking was improved. The control parameters were optimized for multiple parameters, which significantly improved the accuracy of trajectory tracking;the random forest algorithm was used to extract the features of the trajectory tracking data, and the algorithm parameters were modified according to the weight of each feature importance index. On an open concrete runway with a maximum horizontal inclination of 2° on the test site, the mass of the tractor was 2t, the mass of the towed machine was 10t, and the length was 22m, and the design of the traction unit required a maximum running speed of 6km/h and a maximum lateral deviation of 50cm. According to the long and complex path test and data analysis, the maximum delay of the system correction response was 84ms, the maximum absolute lateral error of the traction unit was 37.14cm, and the average absolute error was 14.91cm, which met the practical application requirements in large-load towing operations.