Taking typical silty soil in Henan area as the research subject, modified silty soil samples with different lime and metakaolin contents were prepared. Unconfined compressive strength tests, scanning electron microscopy(SEM) and X ray diffraction(XRD) tests were carried out, and the comparison analysis was made with the hydraulic lime modified silty soil. The results show that with the increase of metakaolin content, the failure strain and unconfined compressive strength of the modified silty soil increase, but the strength growth rate increases first and then decreases, which reaches the peak value when the metakaolin content is 4%. When the curing age increases from 7d to 28d, the strength growth rate of lime metakaolin modified silty soil is significantly higher than that of lime modified silty soil. 6% lime +4% metakaolin and 8% lime +4% metakaolin can effectively replace 8% and 10% hydraulic lime respectively. The hydration products formed after the incorporation of metakaolin can bond soil particles and fill in the pores, which makes the microstructure of the improved silty soil more compact and has certain hydraulicity.