In order to avoid the collapse fault in power system caused by the influence of human or natural factors, the present paper designed a monitoring protect system of key electric feature parameters in power system based on embedded system. In this paper, it deduced the transformation algorithm between the effective and instantaneous measure values and the algorithm among the electric feature parameters in power system, taken the microcomputer line protection system of a 110kV substation as an example, it constructed the software and hardware platform of feature parameter status monitoring based on embedded microprocessor, respectively, and accordingly designed the hardware circuit and software control program. The results demonstrated that the designed system can correctly judge the fault of the related devices and send the trip command to make the isolation between the fault device and the power system so as to protect the system from being damaged. The experiment results show that it is effective and available approach to the early warning of electrical feature parameters.