With unconfined compressive strength and shear strength as the main index, the influence of different amount of manufactured sand and water glass on unconfined compressive strength, rigidity and shear strength of expansive soil in Nanning, Guangxi are explored through experiments. The soil sample’s dry density is 1.65g/cm_³, and the water content ratio is 15%. The results show that the unconfined compressive strength and rigidity increase firstly and then decrease with the increments of the manufactured sand and water glass amount when they are added separately. The optimum addition amount of manufactured sand is 10%, and the strength increases by 15.7% (control the particle size of the sand is less than 0.5mm). The optimum addition amount of water glass (sodium silicate) is 1%, and the strength increases by 52.4%. However, the manufactured sand will reduce the improvement effect of water glass when the compound substances are added. Further study explored the effect of the particle size of the manufactured sand on the unconfined compressive strength of expansive soil. The results show that the particle size of the manufactured sand should not be greater than 0.5 mm in order to increase the strength of the expansive soil. According to the direct shear test and Mohr-Coulomb strength theory, it is proved that two methods both can improve the shear strength of expansive soil. The research verifies the effectiveness of water glass modified expansive soil and manufactured sand instead of natural weathered sand to improve expansive soil, which can provide a reference for the future improvement of expansive soil.