The behavior of engine automatic starting and stop under idle speed is an important working model for HEV(hybrid electric vehicle), which can avoid engine running under idle speed. So it can reduce engine fuel consumption, exhaust gas emission and wear efficiently. The ISG(integral starter/generator) motor control strategy is given by dynamic research of the HEV engine starting, based on the model and simulation of resistant characters during engine starting, then an ISG motor-engine integral control model is built up and simulated. The result shows that the ISG motor can drive engine quickly and the simulation meets well with the need of starting time.