The invention discloses a machining process of a 5083-O aluminum alloy DOOR. The machining process is characterized by comprising the following steps that (1) a machining portion is effectively supported and fixed; (2) uniform locating and locking are achieved; (3) continuous cutting is achieved in the machining process, and cutter vibration is avoided; and (4) an application tool is simple, and operation is convenient and fast. The machining portion is effectively supported and fixed in the step (1), and the situation that no supporting edge strip exists in the machining process, cutter vibration happens after machining through operation, and part overcut is caused is avoided. In the step (2), uniform locating and locking are achieved, interrupted arrangement is achieved, cooling liquid and aluminum chips are smoothly discharged out in the machining process, and the situation that chips are left in the part machining process, and parts are damaged is effectively avoided. Cutter holesare drilled in the two ends of a deep groove, direct cutting is achieved, reciprocating non-cutter-lifting machining is adopted, the deep groove is machined through a long cutter and a short cutter, and the machining speed is effectively increased. Operation is convenient, the technical requirements for overall locking work are low, and the requirements for operation workers are effectively reduced.