The foamed mixture lightweight soil was prepared by tailings. The effects of wet density and tailings concent on the mechanical property and frost resistance of lightweight soil were researched, and the effects of tailings on the pore structure of lightweight soil were researched. The results show that the compressive strength of foamed mixture lightweight soil is positively correlated with wet density and negatively correlated with tailings content. When the content of tailings reaches 45% （mass fraction, the same below）, the compressive strength of light soil with 700 kg/m3 and 800 kg/m3 wet density is 0.97 MPa and 1.40 MPa respectively, which is about 69% and 66% lower than that of lightweight soil without tailings. Tailings foamed mixture lightweight soil has good frost resistance. In 30 freeze-thaw cycles, the loss rate of compressive strength of lightweight soil with 700 kg/m3 wet density of 0% to 45% tailings is less than 15%, and the compressive strength is greater than 0.80 MPa. Improving the wet density grade can further improve the frost resistance of lightweight soil. The addition of tailings will increase the porosity and average pore diameter of lightweight soil and reduce the pore roundness. Compared with the lightweight soil without tailings, when the content of tailings reaches 30%, the porosity increases by 3.58%, the average pore size increases by 16.7%, and the roundness increases by 7.4%.