In order to reduce the shock and vibration caused by the torque disturbance of gearbox in the process of in situ shift for vehicles equipped with automatic transmission， the design and analysis method of a novel semi-active hydraulic damping strut （HDS） is put forward. Firstly， the shock and vibration mechanism of in-situ shift is theoretically analyzed. Secondly， the dynamic response evaluation indexes are constructed， and the vehicle dynamic model with13 degrees of freedom （DOFs） is established including semi-active HDS. The dynamic characteristic parameters of the semi-active HDS are optimized based on the method of force sharing. Finally， the dynamic response evaluation indexes with and without semi-active HDS are analyzed using the 13 DOFs vehicle dynamic model in situ shift process， and the acceleration of seat rail is tested by experiments. The study results show that the shock and vibration of the vehicle is reduced by introducing the semi-active HDS.