A power system for a hybrid vehicle includes a first planetary gear mechanism and a second planetary gear mechanism that cooperate with each other, wherein a first sun gear rotates with a first input shaft, a second sun gear and the first input shaft are independent from each other, the second sun gear achieve different movement states through a first brake, a second brake and a second clutch, to provide different transmission ratios, so that the power system is simple in structure, low in cost and more flexible in adaptability. Further, a second electric motor is connected with the first input shaft through a third planetary gear mechanism, can reduce the speed of the second electric motor through the planetary gear mechanism, and increase the torque, to effectively reduce the size of the second electric motor or improve the acceleration performance of the vehicle.