Creep experiment has been carried out about hot continuous rolled 403Nb steel, and microstructures before creep and after creep has been studied, results show that: the dynamic recovery and dynamic recrystallization of 403Nb heat resistant steel occurs during hot continuous rolling, in the phase composition, Cr23C6 is mostly secondary carbide, however, NbC is mostly first carbide. During hot continuous rolling, first carbides restrict from dynamic recovery by keeping dislocation from sliding, and microstructure after dynamic recovery is influenced by the distrbution of carbides. The carbides in the matrix prevent dislocation from moving, and pin effect of the carbides in the grain boundary keep grain boundary from sliding, and creep resistance of steel is improved.