The utility model provides an LED (light-emitting diode) flashlight with a magnesium-air battery. The LED flashlight comprises a housing, an LED lamp base and the magnesium-air battery, wherein the housing comprises a cylindrical shell, a rear cover and a flashlight switch; the rear cover is arranged at the rear end of the cylindrical shell, and is provided with a spring; the flashlight switch is arranged on the outer wall of the cylindrical shell; the front end of the cylindrical shell is connected with the LED lamp base; a clamping groove is formed in the LED lamp base; the magnesium-air battery comprises a metal fuel rod, an air electrode and electrolyte; the metal fuel rod is arranged between the clamping groove of the LED lamp base and the spring of the rear cover, and is fixedly arranged in the cylindrical shell through the clamping groove and the spring; the air electrode is fixedly arranged on the inner wall of the cylindrical shell through a clamping plate; the air electrode, the rear cover and the LED lamp base form a closed cavity in which the electrolyte is arranged. According to the LED flashlight, the magnesium-air battery is used as an energy carrier, and has the advantages of lightweight, simple structure, long cruise duration and short charging time.