The invention relates to a preparation process of a phthalocyanine blue 15:2 pigment for automotive paint and belongs to the technical field of preparation of automotive paint. The preparation process comprises the following steps: firstly, adding a copper phthalocyanine crude product, a copper phthalocyanine derivative and a pigment stabilizer into a grinding machine, and grinding and activating to prepare crystallization-resisting activated copper phthalocyanine; stirring the crystallization-resisting activated copper phthalocyanine, sulfuric acid and the copper phthalocyanine derivative, diluting, washing with acid, washing with water, washing with alkali and filtering and rinsing to obtain a crystallization-resisting phthalocyanine blue 15:1 pigment filter cake; finally, stirring the crystallization-resisting phthalocyanine blue 15:1 pigment filter cake and the copper phthalocyanine derivative to generate paste; pressing and filtering the paste to obtain a filter cake; finally, spraying and drying the filter cake by utilizing a spraying dryer; finally, preparing the crystallization-resisting and flocculation-resisting phthalocyanine blue 15:2 pigment. The pigment is applied to the automotive paint so that crystals formed by the paint and flocculated and agglomerated particles formed by the paint can be prevented; uniform color and luster of the automotive paint are easy to form.