The invention provides a CpG motif with immune-enhancing function on a pig body DNA vaccine. A series of CpG motif is manually synthesized to immunize pig bodies; and through measuring the cell immune level and the humoral immunity level of the CpG motif, an optimal CpG motif is determined for pigs, and the CpG motif can be used as a DNA vaccine adjuvant to further enhance the immune effect of the DNA vaccine. The CpG motif as an immunopotentiator has the advantages of simple preparation method, easy storage and transportation, easy quality control, easy mass production, low cost, easy storage and transportation, and good safety. A cell factor is an immune regulating molecule inherent in an organism, has no toxic side effects to human body, and is also controlled by an organism immune regulating network; besides, the CpG motif is easy to build and transform, and the immune response strength and types expected by people can be achieved at gene level through a molecular biology technology.