The invention discloses a machining method for a PH13-8Mo part used for aviation. The machining method includes the following steps that firstly, a PH13-8Mo bar is subjected to blanking and blank manufacturing and subjected to at least one time of die forging and edge cutting, a forge piece in a certain shape is formed, annealing is conducted at the temperature being 600 DEG C to 760 DEG C, and residual stress in the forging process is eliminated; secondly, the forge piece is subjected to solution treatment; thirdly, the forge piece is subjected to cold treatment; fourthly, after cold treatment is completed, the forge piece is subjected to rough machining, and a blank part is formed initially; fifthly, the manufactured blank part is subjected to manual aging treatment; and sixthly, finishmachining is conducted on the blank part, and a finished product is manufactured. By means of the machining method, a cold and heat combined technology scheme is adopted, the part is subjected to rough machining in a solid solution state, removing work of most of materials is completed under the low hardness, the cutting speed is increased, and the tool loss amount is reduced; and the equivalent thickness of the forge piece obtained after rough machining is reduced, the heating time and energy consumption of subsequent manual aging are reduced, furthermore, heat correction can be conducted onpart deformation, part of machining stress is eliminated, and part deformation is reduced.