Abstract: To decrease the radiation heat load of the cryopanel is conside red to be necessary for the design of cryopumps.Generally,a radiation baffle is mounted between cryopanel and heat resource.A majority of the radiated heat load is absorbed by the radiation baffle.However,the motion of molecules to be pumped is baffled and the pumping speed is lowered.Therefore the selection of rad iation baffle is very important issue for the economical operation of the cryopump.Monte Carlo method is used to calculate and synthetically analyze the thermal transmission coefficient and the molecular transmission coefficient of two different structural radiation baffles.The reasonable type of Chevron baffle is obtained.By calculating the radiation heat load of the cryopanel,it is proved that the radiant heat load of the cryopanel can be cut down by the radiant baffle. The effect is remarkable.