Abstract: Aiming at the problem of lower efficiency in section method for complex mesh surface machining,an algorithm for spiral tool path generation is proposed.Mesh surface is parameterized firstly by harmonic map method,then parametric loops are calculated in parametric mesh by scallop height,points of adjacent parametric loops are matched group by group,and initial,exact diagonal parametric spiral curves are calculated in sequence.Based on these,free-interference spiral tool paths are generated rapidly by region segment method for mesh surface machining.Experimental result indicates that machining efficiency of spiral tool paths is improved effectively with better machining quality,compared with section plane tool path for complex mesh surface machining.