Total dose effects can affect obviously ROIC′s performance and even make its function fail.Frist,the mechanism of total dose effect on the threshold,leakage current and inter-device leakage current of NMOS devices is analyzed.Then,the hardening radiation design methods for 640×512 ROIC chip is proposed.Total ionizing dose experiment shows that the ROIC’s radiation tolerance,using enclosed gate geometry and ringed-source geometry,is beyond 100 krad(Si).