A safety rack regulating device for nailing guns comprises a regulating base, a guide slot located in the left part of regulating base, and a safety rack located in the guide slot. The left end of safety rack is extended out of the regulating base and provided with a safety head. A square groove is located in the left part of the regulating base. A clamping cap is located in the regulating base, the clamping cap seals the opening of square groove. The enclosure between the clamping cap and inner wall of regulating base forms a guide hole. A suited adjusting bolt is located in the guide hole. A transverse punch hole is located in the center of the adjusting bolt. A regulation hole corresponding to the position of adjusting bolt is located in the outer wall of the regulating base.