Abstract: In view of the lack of obstacle detection and avoidance methods in the process of autonomous navigation of traditional orchard vehicles, and the inability to avoid obstacles in time, a set of orchard vehicle navigation obstacle avoidance system based on PX4 and ultrasonic sensors is designed. I The system is based on the Pixhack flight control processor and GPS sensor to build an orchard automatic navigation system to realize the autonomous cruise function of the vehicle between the orchards; and uses the Arduino control board and the US-100 ultrasonic ranging module to build an ultrasonic obstacle avoidance module, which is intended to solve the PX4 The obstacle avoidance problem in the automatic cruise process of the navigation system uses the ultrasonic sensor to measure the distance of the obstacle in front of the vehicle. When the distance between the two is less than the safe distance set by the system, the obstacle avoidance algorithm is executed, and the ultrasonic module is controlled to rotate through the steering gear. The obstacle is located on the left or right side of the vehicle, and the control panel drives the vehicle to move to the side with no obstacles. If there are obstacles within a safe distance on both sides, the vehicle is driven to retreat beyond the safe distance. In addition, in order to solve the problem of the execution of flight control signals, remote control signals, and ultrasonic signals at the same time, a priority decision method is introduced to solve the compatibility problem of each signal by setting the execution order of different signals in the three modes. The test results show that when the safety distance is set to 2m, the minimum actual safety distance deviation is 0.02 m, the maximum is 0.21 m, and the average deviation is 0.14 m. It can solve the problem of different signal execution order and meet the obstacle avoidance requirements of the actual orchard.