Laser ranging is a widely used laser technology.It has many advantages, such as convenient operation, high precision, and the ability to use it anytime and anywhere.In this paper, a portable laser ranger based on STM32 is designed, which can perform high-precision ranging function under complicated working conditions.The system is composed of 4 modules, including STM32 module, laser ranging module, WT588D voice module and TFT LCD module.The system also measures the time of laser flight (and the phase difference of the echo), and the measurement results can be accurate to thousands of points, thus ensuring the accuracy and reliability of the ranging.