Hardened steel is typically low-machinability mold material

strong thermal and mechanical loadingin the processing process，lead to cutter wear and breakage，and reduce the mold machining surface quality. In or-der to improve the machining surface quality and cutter life，studied the design of torus end milling cutter with cir-cular corner. Firstly，combined with the ball end milling cutter and annular cutter cutting property，proposing akind of applicable to large hardened steel mold machining with torus end milling cutter with circular corner. Sec-ondly，torus end milling cutter with circular corner geometrical features are defined，establish mathematical modelof milling cutter contour surface，which is derived from the helix edge parameter equation. Finally，torus end mill-ing cutter with circular corner is tested by simulation，cutter grinding experiment and test center，the result showthat cutter diameter，fillet radius，radius of cutter with circular corner design，cutting edge grinding accuracy errorrange of the cutter in the range of 1 0. 001 mm，and the error range of the grinding error is within 1 0. OS，providetechnical support for the popularization and application of cutter.