A biodegradable bone nail, including a rod-shaped magnesium screw having a head including a cross groove. The magnesium screw includes an axial chamber disposed below the cross groove, and a depth of the axial chamber is two thirds that of the bone nail. Along the length direction of the axial chamber, a plurality of radial holes are equidistantly disposed every 90 degrees from the bottoms of threads on the wall of the magnesium screw, and the radial holes communicate with the axial chamber.
