The invention provides a piston rod reset mechanism of a jack and the jack. The piston rod reset mechanism is used for resetting a piston rod of the jack and comprises an air source supply device, an unloading control mechanism and a controllable one-way valve, the piston rod is provided with a piston head, the jack comprises a hydraulic cylinder, the piston head is located in the hydraulic cylinder and divides the hydraulic cylinder into a cavity with the piston rod and a cavity without the piston rod, and an oil outlet oil passage is arranged in the cavity without the piston rod; the unloading control mechanism is connected to the air source supply device; the controllable one-way valve is arranged on the oil outlet oil passage and connected with the unloading control mechanism; the cavity with the piston rod is connected with the air source supply device or the unloading control mechanism. When the piston rod reset mechanism of the jack and the jack are used, the piston rod is pushed to conduct resetting through an air pressure mode, the resetting speed of the piston rod is fast, and the stability of the resetting is good; meanwhile, a return air passage is arranged inside an oil tank and combined with the oil tank to be a whole, so that the overall size of the hydraulic jack is small, the appearance is attractive, the operation is convenient, and the usage requirements of the hydraulic jack are met for people.