A low-pressure mold for improving performance of spokes of an aluminum wheel. The mold is characterized in that cooling air holes in a bottom mold are moved for 10 mm outwards; heat-insulation grooves are formed in positions, 5 mm from the cooling air holes, of a back cavity of the bottom mold, and are 8 mm from the surface of a cavity; and the width of each heat-insulation groove is set to 8 mm. A circumference arrangement range of the heat-insulation grooves needs to be larger than the widths of the spokes, and the number of the heat-insulation grooves is defined by the number of the spokes. Heat-preservation asbestos is arranged in each heat-insulation groove, thereby further strengthening heat-insulation and heat preservation functions. One air hole is added based on the prior art, thereby increasing the cooling area and improving the cooling intensity.