The invention relates to a bottom grouting system suitable for a deep well grounding electrode steel sleeve and a grouting method. The grouting system is composed of a bottom steel column, an inner layer well screen, an outer layer well screen, a grouting socket, a one-way valve, a grouting tap, a drill rod and the steel sleeve. When the grouting system starts grouting, the one-way valve is started by the pressure of the grouting tap, so that the water in the outer layer of the steel sleeve is timely supplemented to the inside of the steel sleeve, and the failure of a feeding system due to evaporation of water caused by temperature rise when a feeding rod drains into the ground is prevented.