Abstract: The paper analysed the status when the motor is running. According to the fault features of motor, it put forward the protection system of motor based on 196 series single-chip microcomputer. It also put up establishment and derivation of mathematical model in algorithm. In addition it carried out optimistic design about hardware and software, especially introduced complex programmable logic device ISPLSI-1032E gate array, which made the system become more concise and stable. The protection system has many characteristics such as rapid velocity, strong anti-interference, powerful protection etc.