【Objective】Study on the optimization of foam agent and its solution and the optimal proportion. 【Method】Through systematic experimental research on the research methods of surface tension,foaming ratio, half-life and stability of foam produced by several typical foam agents, the performance index and concentration value of foam agent for optimization were proposed. On this basis, with the C40 cement soil mix ratio as a reference, the prepared foam and C40 cement slurry are mixed according to different injection volume ratios, their dry and wet weight are measured, and the proportioning scheme of lightweight foam concrete under different design weight conditions is determined. Further, unconfined compressive strength tests were conducted to determine the compressive strength of lightweight foam concrete test blocks under different gravity conditions,and electron microscope scanning tests were conducted to understand their microstructure.【Result】The results showed that the optimal concentration of different types of foam agents was about 3%, the foaming ratio was 25, the surface tension was 32 mN/m, and the half-life was 15 minutes; The density and strength of lightweight foam concrete decrease significantly with the increase of foam injection rate,and the corresponding bubble group content and pore size dispersion increase significantly.【Conclusion】Dry density of lightweight foam concrete and the injection rate are in an exponential relationship of attenuation type, and the unconfined uniaxial compressive strength and the dry density of lightweight foam concrete are approximately in an exponential relationship of non gentle increase type.