The invention relates to an electro-hydraulic damping cylinder device applied to an intelligent knee joint. The device comprises an open cylinder body (2), a cylinder cover (1), a piston valve (4), an upper piston (3), a lower piston (6), a guide piston rod (5), an upper piston rod (10), a valve core rod (9), a step motor (7) and a spring (8), wherein the cylinder cover (1) is covered on the opening of the cylinder body; the piston valve (4) is fixed at the middle position of the cylinder body (2) and positioned between the upper piston (3) and the lower piston (6); the upper piston (3) and the lower piston (6) are positioned in the cylinder body (2) and in contact connection with the inner wall of the cylinder body (2); the guide piston rod (5) passes through the piston valve (4) to connect the upper piston (3) and the lower piston (6); the upper piston rod (10) is arranged on the upper piston (3) and passes through the cylinder cover (1) to connect with the knee joint; the valve core rod (9) is matched with the piston valve (4); the step motor (7) is connected with the valve core rod (9); and the spring (8) is arranged at the bottom of the cylinder body (2). The device can realize bidirectional damping control on a hydraulic cylinder by using a motor.