The Magneto Rheological Fluid, MRF is a reversible material, this material would be an idea semi-active control device due to its reversible and easy-control properties. In this research, Solid Works 3D drawing software is used as the structural design and Max Well magnetic field analysis software is used to simulate the lines of magnetic force toward the innovation design "semi-active spiral flow channel magneto rheological damper" to improve the heat dissipation and the problem of precipitation. The Performance test of semi-active spiral flow channel magneto rheological damper uses ball screw and AC Servo Motor as actuator, the servo control system's function of displacement recorder and load cell as recorder of damping force. The spiral flow channel MR damper is an innovative design, the spiral flow can not only increase the length of the flow channel in a fixed distance, but also changes the excitating paramagnetic particles direction to be vertical with the direction of flow, and thus increases the ultimate shear strength of MRF. Without applying magnetic field, the spiral flow channel MR damper can generate the maximum damping force of 103N. When the current is 3A, the maximum damping force is about 1970N, when the damping force adjustment coefficient is 4.88(=1970/403), the damper is with high range of adjustable damping force. Most importantly, this design establishes a simple structure with lower cost.