The invention relates to a phase-change energy-storing cooling battery module comprising a plurality of electric core modules arranged in series; each electric core module comprises a shell body and a plurality of electric cores arranged in the shell body, four electrical cores form a group and are distributed in an upside-down T-shaped shape, and the center of each group of the electric cores is inserted with a thin-wall expansion aluminum tube in a penetration manner; each thin-wall expansion aluminum tube has a hollow cylindrical structure with one end opening and is filled with a composite material, and an opening tube of each thin-wall expansion aluminum tube is sealed by a plug; the composite material is composed of paraffin and expanded graphite; the paraffin is a PCM material, has relatively high phase-change latent heat per unit mass, has a high melting temperature in a battery operating temperature range and has relatively low cost; but pure paraffin has poor thermal conductivity, so the expanded graphite is added to improve thermal conductivity rate and increase natural convection cooling effects.