The invention discloses a reinforcement cage for a cast-in-place pile with an oversized tip, which comprises a plurality of longitudinal reinforcing steel bars distributed along the same periphery, and a plurality of annular reinforcing steel bars distributed along the vertical direction and connected with the longitudinal reinforcing steel bars; the longitudinal reinforcing steel bars positioned in a hole enlarging section of the cast-in-place pile are evenly distributed with radial divergence reinforcing steel bars; each divergence reinforcing steel bar is formed by bending a straight reinforcing steel bar to have an upper vertical section, a horizontal section and a lower vertical section; the divergence reinforcing steel bars are hinged to the longitudinal reinforcing steel bars or the annular reinforcing steel bars; the longitudinal reinforcing steel bars are provided with a clamping positioning mechanism respectively corresponding to each divergence reinforcing steel bar; a positioning clamp and a positioning plate are respectively welded on the outside and the inside of each longitudinal reinforcing steel bar; the front side of the positioning clamp positioned on the lower part is provided with an opening groove into which each divergence reinforcing steel bar is clamped; the lateral surface of the positioning clamp is provided with a blind hole which passes through the opening groove and extends outwards; and a bolt, a spring and an adjusting screw are orderly arranged in the blind hole from inside to outside. A hole enlarging pile with the oversized tip formed by the invention has the advantages of large stressed area on pile bottom, high load bearing capacity of a single pile and strong seismic capacity of the bottom of the single pile.