Abstract: For problems of incorrect ranging caused by interference and high cost of existing collision avoidance system of mine locomotive, a collision avoidance and ranging system of mine locomotive based on laser ranging was designed by use of STC90C516RD+ single chip microcomputer and TDC-GP1 timing chip with high precision. Ranging principle of the system and design schemes of software and hardware were introduced. Ranging test was done for the system in range of 20-100 m with the max original ranging error of 0.22 m. After being linearly fitted and corrected in Matlab by use of the least square method, ranging errors were less than 0.03 m and satisfied ranging requirement at locomotive running.