The traditional multistage hydraulic cylinder has many disadvantages,such as working pressure is small, thrusts at all levels are small and unequal, one way out distance of piston rod is long, deflection is large, stability and reliability at work are poor, service life is short and etc.To overcome the defects, the whole structure was redesigned. Different cylinder diameters and piston rod diameters were adopted, through reasonable arrangement and combination of internal oil distribution base, three stage equal thrust was achieved and the thrust was larger. Bidirectional extended structure of piston rod was adopted,then oneway out length of the piston rod was short,the out deflection was small, to prevent the parts to be injured. Through the above improvement, the stability and the service life of the hydraulic oil cylinder are greatly increased.This product has won a patent for invention(ZL201310691041.5).