Abstract: In response to the problem that traditional intelligent cars cannot operate autonomously in complex real-world environments, we design an intelligent car that can automatically avoid obstacles and can run along a specific trajectory. The design is based on the STC89C52 microcontroller as the core, two sets of the reflective photodetector (RPR220) and ultrasonic distance measurement module (HC-SR04) are applied to sense the black trajectory and obstacle information respectively, and the detection information is transmitted to the microcontroller. After that, the speed and direction of the car motor are adjusted by the microcontroller and its peripheral circuit to realize the tracing and obstacle avoidance functions of the intelligent car. The experimental results show that the modules of this design can work together normally and can realize the tracing and obstacle avoidance functions of the car. In addition, the car has safe and stable operation, and wide application prospects.