Prestress expansion shell type anchor rod

The utility model discloses a prestress expansion shell type anchor rod which comprises a main rod part and an expansion shell part. The expansion shell part comprises a shell and expansion shell teeth, the shell is provided with an insertion end and a first connecting end which are opposite to each other, the connecting end is connected with one end of the main rod part, the expansion shell teeth form movable ends and second connecting ends, the second connecting ends of the expansion shell teeth are rotationally connected to the shell, the movable ends of the expansion shell teeth define a contraction space, and an opening of the contraction space faces the first connecting end. Wherein the insertion end is used for being inserted into an insertion hole formed in the surface of tunnel surrounding rock. According to the technical scheme, when the prestress expansion shell type anchor rod is tensioned backwards, the included angle B between the expansion shell teeth and the tensioning direction is smaller tha