The utility model relates to a rotary knob switch device of a helmet safety warning light. The rotary knob switch device of the helmet safety warning light comprises a rotary knob switch body, a rotary knob bottom shell which is arranged on the rotary knob switch body in a surrounding way and a transparent circular-shaped rotary knob outer shell arranged outside of the rotary knob bottom shell, wherein the rotary knob switch body is provided with a luminous light source, the inner wall of the rotary knob outer shell is provided with a reflecting coating, the reflecting coating is arranged at the inner wall of the rotary knob outer shell in the surrounding way, and an angle between the reflecting coating the inner wall of the rotary knob outer shell is 30-60 degrees. According to the rotary knob switch device of the helmet safety warning light, disclosed by the utility model, the transparent circular-shaped rotary knob outer shell is adopted, the rotary knob switch body is provided with the luminous light source, the inner wall of the rotary knob outer shell is provided with the reflecting coating, and the reflecting coating is arranged at the inner wall of the rotary knob outer shell in the surrounding way, thus a whole rotary ring is luminous when the rotary switch device is used, and the use is convenient.