Abstract: 4A sub-micron molecular sieve was synthesized by sol-hydrothermal method with wet silica gel and bauxite as raw materials.Prepared 4A sub-micron molecular sieve was characterized by XRD,SEM,and FT-IR etc.and it was also compared with the samples prepared by common hydrothermal method.Results showed that crystallinity of the product was 96%;shape of the product was in rules,which had uniform and single size;distribution was Gaussian distribution and distribution range was narrow;crystal size was small and volume fraction of particles less than 1 μm reached 100%;calcium exchange capacity of the product (dry basis) was 335 mg CaCO3/g and whiteness was 97%,which made the product totally suitable to be used as detergent builder.