The invention discloses an automobile kinetic energy conversion and recovery device. The automobile kinetic energy conversion and recovery device is used for storing energy during subway braking and recovering kinetic energy during starting. The automobile kinetic energy conversion and recovery device mainly comprises an eccentric wheel, hydraulic plungers and a corresponding hydraulic loop. During subway braking, the eccentric wheel and an axle rotate synchronously, so that the built-in hydraulic plungers conducts reciprocating radial motion; hydraulic oil is pressed into an energy accumulator through the hydraulic plungers on the basis of the design of the corresponding hydraulic loop, and therefore kinetic energy of the automobile is converted into hydraulic energy to be stored. During subway starting, the device is used as a low-speed large-torque hydraulic motor on the basis of switching control over an electromagnetic valve to push a subway to achieve kinetic energy recovery. According to the automobile kinetic energy conversion and recovery device, the hydraulic mode is utilized for energy storage, braking energy is not converted into electric energy and is just stored as hydraulic energy, and the efficiency is much higher than that of the existing energy storage mode.