The invention discloses a machining method for composite manufacturing of a turbine blade in additive and subtractive modes, and relates to a machining and manufacturing method for the turbine blade,in particular to a composite machining method for manufacturing the turbine blade in the additive and subtractive modes. The machining method for composite manufacturing of the turbine blade in the additive and subtractive modes comprises the steps of additive forming and subtractive machining, wherein additive forming and subtractive machining are conducted alternately and circularly. Additive forming comprises the steps that A1, integral modeling and layering are conducted; A2, local special layering is conducted; A3, the additive path is planned; and A4, single-cycle additive machining is conducted. Subtractive machining is divided into two machining types of end milling and side milling, and according to the different machining types, subtractive machining comprises the steps that B1,a machining area is divided; B2, process parameters are set; B3, local special parameters are set; and B4, single-cycle subtractive machining is conducted. Additive forming and subtractive machining are circularly repeated till the whole turbine blade is completed. The machining method for composite manufacturing of the turbine blade in the additive and subtractive modes has the characteristics that the method is novel, the process is simple and convenient, the machining precision is improved, particularly detail feature finish machining is achieved, the machining efficiency is improved, and the application range is wide, and integrates economical efficiency and practicality.