A kind of intelligent and compositive motor protector designed by ATMEGA16 single-chip microcomputer was introduced. The product, which has a set of high precision, high sensitivity and reliability, has many functions, such as overload or lightload protection, phase loss, overvoltage or lightvoltage, short circuit, locked rotor, leakage and phase imbalance protection. This product is a perfect substitute to the traditional motor protection devices, which has a good cost performance and broad market prospects.