Abstract: In order to improve the precision of simulation of helical milling with round blade cutter,a higher-order accurate numerical method for Z-map milling simulation is proposed.Based on the geometric mechanism of the cutter's spiral motion,cutting area is divided into single-value parts and the mesh point of the cutting area is searched quickly.Mathematical formulas are deduced,which are suitable to high-accuracy calculation of z value of the Z-map grid points,and ensure the iterative numerical calculation has a square convergence rate.Results of the simulation example show that the cutting simulation is guaranteed at a satisfactory speed,and this method evidently enhances the simulation precision of round blade cutter helical milling.