Abstract: This paper describes the principle and software of micro computer control system of PJ-1 China's first spray painting robot with micro computer control and multi-articular manipulator and electro-hydraulic servo.This system uses a single 8-bit microcomputer and enjoys the support of REX,a uni-user multi-task real time operating system.The method of grouping storage of absolute positions and sample interval increments is adopted.Thus,the difficult problem of storage resulted in the large memory capacity needed by spray painting robot is essentially solved.