In the battery management system,the battery state parameter monitoring system is the basis to ensure its normal operation. Based on the needs of the electric vehicle power battery management system, a power battery state parameter monitoring system is designed with the DSP28335 chip. With more tests verification, the system can monitor the total voltage, monomer voltage, total current and multipoint temperature of the power battery, and the the monitoring circuit is simple, low cost, high precision. In addition, the voltage and circuit measuring circuit is designed with optocoupler to isolate the power battery high voltage and current impact during the monitoring process. In this way, the safety has been guaranteed.