Control method of cold start of hybrid power system

The invention discloses a control method of cold start of a hybrid power system, wherein, an electric machine participates in starting an engine if the water temperature of the engine is higher than the presupposed threshold value of water temperature, the sate of charge of high pressure battery is higher than the presupposed threshold value of a first sate of charge and the available discharge power of high pressure battery is higher than the presupposed threshold value of a first available discharge power; otherwise, a starter starts the engine solely. The invention adopts the cold-start control method of the hybrid power system to start the engine, and if conditions are allowable, the electrical machine and the starter can be used jointly to start the engine, thereby increasing the torque when the engine starts; moreover, the smaller overshoot of the engine enables that the engine starts more smoothly, which is able to effectively lessen the vibration and noise in the process that the engine starts, decrease emission and oil consumption, reduce pollution and save energy.