Abstract: The orifice plate throttling pipeline with large pressure drop suffers damages from high frequency vibration caused by cavitation and low frequency vibration caused by high flow velocity. Aim at solving the vibration phenomenon of typical throttling pipeline with large pressure drop in KBA system of nuclear power plant, the key hydraulic characteristics such as pressure drop, flow velocity, streamline and eddy current were simulated and analyzed for single-stage orifice plate throttling pipeline based on CFD method. The negative pressure area was found in the downstream of the orifice plate, which means cavitation occurred, and eddy current was formed due to the large local velocity caused by the orifice plate jet. Then, the throttling performance of multi-stage concentric orifice plate was evaluated by means of blockage pressure drop method. The cavitation damage was found to be relieved greatly but not eliminated especially in the last stage orifice plate. The expanding type five-stage orifice plate was designed according to pressure drop stage-decreasing principle, with which the possibility of cavitation was eliminated but large pressure drop resulted in large flow velocity at the downstream of the first orifice plate. Multi-stage eccentric orifice plate was designed considering cavitation characteristics and velocity distribution, which can not only eliminate the harm of cavitation, but also reduce the low frequency vibration caused by large flow velocity furthest. By increasing the spacing of the orifice plates, the throttling capacity of the upstream plates can be increased and the cavitation margin of the downstream plates can be improved. As a result, multi-stage eccentric orifice plate can be recommended as an optimized design scheme for the vibration control of the orifice plate pipeline with large pressure drop.