Abstract: As an important part for ITER,shield block is used to shield the neutron heat.The structure design of shield block,especially the inner coolant channel design will influence its cooling effect and safety significantly.In this study,the thermal-hydraulic analysis for shield block has been performed by the computational fluid dynamics software,some optimization suggestions have been proposed and thermal-hydraulic characteristics of the improved model has been analyzed again.The analysis results for improved model show that pressure drop through flow path near the inlet and outlet region of the shield block has been reduced,and the total pressure drop in cooling path has been reduced too;the uniformity of the mass flowrate distribution and the velocity distribution have been improved in main cooling branches;the local highest temperature of solid domain reduced considerably,which could avoid thermal stress becoming too large because of coolant effect unevenly.