The shielding design employing the Monte Carlo simulation code of MCNPX 2.5.0 for multi-purpose reflectometer of China spallation neutron source(CSNS) is introduced, including the shielding needs, radiation source terms, calculating methods and simulation results, etc. Various radiation source terms such as the moderator leakage source term, and the neutron guide loss source term etc. are taken into account in the simulation, and step-by-step calculation method and variance reduction methods such as source ...