The Yulin city wall is one of the sixth group of key cultural relics under national protection. In order to improve the soil strength, durability and other performance, the chemical composition of city wall soil was analyzed firstly, finding out that the soil in the city wall contains a special local construction material called liaojiang stone which is native to both the loess area in northern and northwest China and in limestone regolith. Then, chemical analysis and salt dissolution analysis were carried out, some amount of mixed stuff（liaojiang stone, cement, hydrated lime） was added into the soil to improve the soils strength, water resistance, salt dissolution resistance, freezing resistance and wind erosion resistance and so on. The research results demonstrate that the rammed wall constructed with the modified soil containing 5%（by mass, the same is below) cement, 5% hydrated lime, 10% liaojiang stone and 80% soil has good durability.