The invention belongs to the technical field of aluminum alloy surface treatment, and particularly relates to a surface treatment method for the highlight edge of an aluminum alloy mobile phone shell. The surface treatment method comprises the following steps of machining of the counter and an inner cavity of the aluminum alloy mobile phone shell, CNC highlight treatment carried out on a frame after surface polishing, surface alkaline washing, surface sand blasting and first-time anodic oxidation, oil removal and cleaning, spraying of printing ink after shielding of the mobile phone shell, printing ink baking, ultraviolet exposure treatment, developing treatment, baking, UV radiation for curing printing ink, second-time anodic oxidation treatment, printing ink removal and third-time anodic oxidation treatment. After the highlight edge of the aluminum alloy mobile phone shell is subjected to three times of anodic oxidation treatment, the portion, close to a display screen, of a longitudinal frame of the mobile phone shell has the same color as the display screen, a frame-free visual sense is formed, the straightness of a color junction edge in second-time anodic oxidation and third-time anodic oxidation is ensured by the adoption of a three-dimensional exposure mode, the production yield reaches up to 90% or above, the cost is low, and production efficiency is high.