The invention discloses a hybrid power transmission system, a control method and an automobile, belonging to the field of hybrid power. The system comprises: first spindle, second spindle, an engine sequentially connected to the first spindle, First clutch, a third gear driving gear, a second clutch, a first gear driving gear, a synchronizer, a second gear driving gear and a second electric motor,wherein the first electric motor, the third gear driving gear, the third clutch, the first gear driving gear and the second gear driving gear are sequentially connected with the second main shaft, and the ratio of the number of the first gear driving gear gears to the number of the first gear driving gear gears is a first gear speed ratio; the ratio of the number of gears of the second gear passive gear to the number of gears of the second gear driving gear is the ratio of the second gear speed; the ratio of the number of gears of the third gear passive gear to the number of gears of the third gear driving gear is the speed ratio of the third gear; the second gear passive gear is connected to the wheel. The synchronizer is combined with the driving gear of the first gear or the driving gear of the second gear, so that the automobile has different speed ratios in various modes and has good fuel economy.