Abstract: 20MnSi steel with a submicrometer ferrite grain size of about 0.20μm was manufactured by four passes of equal channel angular pressing via route C at room temperature, and the effect of annealing temperature on the ECAP deformation microstructure was examined. The results show that with the annealing temperature increased, the ECAP deformed microstructure is evolved into recrystallized grains insitu. At annealing temperatures of 300-500℃ for 1 h, the submicrometer ferrite microstructure is relatively stable with negligible grain growth. At annealing temperatures above 500℃, the ferrite grain starts to grow significantly, and there is an average grain size of about 8μm after annealing at 650℃ for 1 h. The cementite in the pearlite by ECAP has a stronger ability of spheroidization at a lower annealing temperature.