The invention belongs to the technical filed of phthalocyanine blue pigment preparation, and particularly relates to a pigment composition containing phthalocyanine blue 15:2 and a preparation methodthereof. The pigment composition is prepared from the following ingredients including phthalocyanine blue 15:0, copper phthalocyanine chloro derivatives and copper phthalocyanine sulfonation derivatives. According to the preparation method, the copper phthalocyanine chloro derivatives, the phthalocyanine blue 15:0 and the copper phthalocyanine sulfonation derivatives are subjected to mixing and pulping and are then subjected to heat treatment at 78 to 85 DEG C; water is added for temperature lowering; press filtering, water washing and drying are performed; a solid is obtained through filtering; a finished product is obtained. The pigment composition and the preparation method provided by the invention achieve the goals of crystallization resistance, color fastness, flocculation resistanceand system viscosity reduction. The prepared phthalocyanine blue pigment has the advantages of high transparency, high coloring intensity, high flowability, high heat resistance and high weather resistance, and can be widely applicable to the fields of printing, paint, ink and weaving.