The invention discloses a forward-backward feeding helical hole milling method of a composite material. A cutter firstly conducts forward helical milling on a front-half-section machining hole and then conducts backward feeding helical milling on a back-half-section machining hole, the defects of layering, tearing and the like, which exceed the machining requirement, of the composite material canbe avoided, and the machining quality is improved. In the hole helical milling pre-machining process, as no base plate exists, machining defects are possibly generated, the machining defects can be cut off in the follow-up backward feeding helical hole milling process, and new machining defects cannot be generated in the process. When the cutter conducts forward feeding helical milling on the front-half-section machining hole, the back-half-section material can serve as a base plate for machining of a front half section, and fiber layers at the position of the composite material cannot generate layering, tearing and other defects; and when backward feeding helical milling is carried out on the back-half-section material, the direction of axial force borne by the composite material is changed, the front-half-section remaining material can serve as the base plate for machining of the back half section, and fiber layers at the position of the composite material cannot generate layering, tearing and other defects.