Abstract: In order to explore the effect of soil lime on seed germination and seedling growth of protective plants,the silty soil of Haiqi highway subgrade in Jiangsu Province was taken as the research object,and Cynodon dactylon,Amorpha fruticosaand Lespedeza were taken as test materials to determine the growth of three plants and the changes of soil nutrient content.The results showed that the plant coverage in the ash soil was significantly higher than that in the non ash soil,and the plant density was extremely significantly higher than that in the non ash soil;the plant height,root length,root surface area and root volume of Cynodon dactylon,Amorpha fruticosa and Lespedezaseedlings in the ash soil were higher than those in the non ash soil,and the plant height,root length and root surface area of the three plants were higher than those in the non ash soil,the root volume increment of Cynodon dactylon seedlings also reached a significant level.After adding lime to the soil,the pH increased by 0.5,and the contents of organic matter,total nitrogen,available potassium and available phosphorus in the soil also increased.The increase of available potassium and available phosphorus reached a very significant level,and the increase of organic matter reached a significant level.The increase of nutrient content in soil mixed with lime provided strong evidence for the promotion of seed germination and seedling growth of protective plants.