A power transmission system for a vehicle, comprising: an engine unit configured to generate power; a dual clutch , wherein the engine unit is coupled with an input terminal of the dual clutch ; a transmission unit adapted to selectively couple with the engine unit , and configured to transmit the power generated by the engine unit , the transmission unit comprising a first input shaft and a second input shaft , wherein the second input shaft is coaxially fitted over the first input shaft , the first input shaft is coupled with a first output terminal of the dual clutch , and the second input shaft is coupled with a second output terminal of the dual clutch , each of the first input shaft and the second input shaft is provided with one fixed driving gear ; an output unit configured to transmit the power output by the transmission unit ; a first motor generator coupled with the one driving gear on the second input shaft via an intermediate gear , wherein the engine unit and the first motor generator are configured to drive the front wheels ; an output shaft , provided with two driven gears , wherein the two driven gears are configured to mesh with the driving gears on the first input shaft and the second input shaft , to form two gears; a synchronizer , disposed on the output shaft , wherein the synchronizer is adapted to enable or interrupt a power transmitting between the transmission unit and the output unit ; a differential cooperating with the output unit for power transmitting, wherein a driving gear of a main reducer is configured to externally mesh with a driven gear of the main reducer, and the driven gear of the main reducer is fixed on the differential , so as to transfer the power to the differential , and the differential distributes power and adaptively transfers the distributed power to half axles at two sides of the vehicle, to drive the front wheels ; two third motor generators configured to drive the two rear wheels respectively. an engine unit configured to generate power; a dual clutch , wherein the engine unit is coupled with an input terminal of the dual clutch ; a transmission unit adapted to selectively couple with the engine unit , and configured to transmit the power generated by the engine unit , the transmission unit comprising a first input shaft and a second input shaft , wherein the second input shaft is coaxially fitted over the first input shaft , the first input shaft is coupled with a first output terminal of the dual clutch , and the second input shaft is coupled with a second output terminal of the dual clutch , each of the first input shaft and the second input shaft is provided with one fixed driving gear ; an output unit configured to transmit the power output by the transmission unit ; a first motor generator coupled with the one driving gear on the second input shaft via an intermediate gear , wherein the engine unit and the first motor generator are configured to drive the front wheels ; an output shaft , provided with two driven gears , wherein the two driven gears are configured to mesh with the driving gears on the first input shaft and the second input shaft , to form two gears; a synchronizer , disposed on the output shaft , wherein the synchronizer is adapted to enable or interrupt a power transmitting between the transmission unit and the output unit ; a differential cooperating with the output unit for power transmitting, wherein a driving gear of a main reducer is configured to externally mesh with a driven gear of the main reducer, and the driven gear of the main reducer is fixed on the differential , so as to transfer the power to the differential , and the differential distributes power and adaptively transfers the distributed power to half axles at two sides of the vehicle, to drive the front wheels ; two third motor generators configured to drive the two rear wheels respectively. <EOS>