A type of compact hydraulic mechanical arm wrist rotating linear actuator was introduced and compared with the existing domestic hydraulic mechanical arm wrist in form and structure,and its unique structure,technical parameters and working principle were described.The hydraulic mechanical arm wrist rotating linear actuator has many features such as compact structure,small size,light weight,high energy conversion efficiency and closed-loop control of the wrist position,which provides reference for accurately controlling the posture of the hydraulic mechanical arm.