The invention is a kind of energy power storage converting energy saving device, it uses the inertia flywheel to generate energy of motion, it can reduce the oil consumption effectively, and it can increase the speed. It includes front speed-variator, orientation flywheel, inertia flywheel, clutch, and backward speed-variator, there sets orientation flywheel, inertia flywheel and the clutch on the output shaft of dynamic force. The orientation flywheel, inertia flywheel and clutch can be fixed on the power output shaft of front speed-variator or between the front speed-variator and the backward speed-variator. The front end of the front speed-variator sets a connecting plate which is fixed with the crank flywheel, there sets a driving gear back of the connecting plate, and it sets a synchronizer, the driven gear is set on the middle shaft and engages with the driving gear, the driven gear engages with the fixing gear on the outer shaft, the first shaft power input shaft has a rolling pin bearing, pushing bearing, cushion, and the second power output connection.