Construction method convenient for breaking pile head of cast-in-place pile

The construction method comprises the steps that before a cast-in-place pile reinforcement cage is installed and concrete is poured, an isolation pipe is installed in a to-be-broken section of the cast-in-place pile head, the outer diameter of the isolation pipe is matched with the inner diameter of the reinforcement cage, and the length of the isolation pipe is not smaller than the height of the to-be-broken section; the bottom of the isolation pipe is flush with the bottom of the to-be-broken section; after the isolation pipe is installed, concrete is poured into the cast-in-place pile reinforcement cage to the top of the cast-in-place pile reinforcement cage, and the concrete formed in the isolation pipe of the to-be-broken section is a cast-in-place pile head; after the strength of the concrete meets the breaking requirement, a plurality of wedge holes are evenly formed in the bottom of the pile head of the cast-in-place pile in the circumferential direction, and a wedge is driven into each wedge hole til