To realize the accurate estimation of battery SOC and increase the precision of battery model, by inoculating standard battery model from equivalent circuit model PNGV battery test manual and based on instrumental variable technique and least squares technique, an online hybrid power metal hydride electric batteries parameters estimation algorithm was proposed to establish battery model using MATLB/SIMULINK. Simulation analysis has shown that the maximal error of battery model voltage is 4.2 V, the mean error is 0.57 V, and the maximal error of the accurate estimate of SOC is 0.048. The mean error is 0.011. It can follow the true data well.