In order to e?ectively reduce the incidence of tra?c accidents caused by drivers' fatigue driving, this paper designs a driver fatigue driving detection system based on EAR algorithm. The system consists of two parts: hardware and software. The hardware part includes STM32 microcontroller, OLED12864 LCD module, DS18B20 temperature sensor module, photoelectric speed sensor module, CN-TTS voice broadcast module, ESP8266 data storage and transmission module and K210 face recognition module. In the software part, EAR detection algorithm is used to detect fatigue. Through the dual monitoring of the single chip microcomputer and the APP running on the mobile phone, the system can monitor the status of the driver in real time, and alert driver when fatigue characteristics is present, so as to e?ectively avoid the safety risks brought by fatigue driving. After testing, the comprehensive accuracy rate of the system reaches 92.4%, which can e?ectively remind drivers to avoid fatigue driving.