Abstract: Using versatile material test machine and split Hopkinson pressure bar (SHPB),quasi-static and dynamic mechanical tests of FeCrNi alloy were carried out,the effect of temperature and strain rate on mechanical properties was investigated.The small ΔG0 of solid solution hardening nitrogen atom made the thermally activated critical temperature Tc lower than the critical descend temperature Tc′ of athermal stress,which resulted in a platform in the quasi-static flow-stress-temperature curve at 573-900K.But high strain rate made Tc higher than Tc′,the platform disappeared.A large mount of annealing twins affected both athermally and thermally activated stresses.The twins disappear as temperature was elevated from room temperature to about 600K,which made the two kinds of stress all descend dramatically in this temperature region.