In the helical milling process, a rotating tool traverses a helical trajectory to generate a hole. In order to investigate the cutting state in helical milling of carbon fiber reinforced polymer(CFRP), experiments were conducted with unidirectional and multidirectional laminates. Cutting forces, tool wear state and hole quality were discussed respectively. The effect of cutting parameters on the cutting forces was first presented, then the influence of different workpiece material on the cutting forces was secondly analyzed. Because of higher abrasion of carbon fiber, tool wear was a major problem without being ignored in the cutting process, so the study on the tool wear state was carried out from the point of wear process, wear form, coated state and change of element etc. Therefore the effect of tool wear on the cutting forces was detailedly analyzed. Next the relation between tool wear and entry delamination of hole-making was discussed. Finally, inner delamination, delamination factor, diameter error, surface roughness and circularity error were also investigated in detail.