There is a large amount of coral soil in Tanzania,and the C value of California bearing ratio as well as the compaction degree can reach more than 80% and 98% respectively,but it is easy to soften after encountering water,and the C values quickly decreases to about 30%.Based on a renovation and expansion project,aiming at the problems of coral soil with high dry strength and softening in contact with water,this paper optimizes the original design of interlock block pavement structure,adopting the coral soil as the base (base) material instead of the traditional cement stabilized or granular base (base) material,and proposes the design of the sole-covered sub-base of pavement structure with Tanzania coral soil,makes checking and analysis based on the finite element calculation theory together with laboratory test research and field typical construction research.The results show that the C values of sole-covered sub-base are most between 70% and 85%,which effectively improves the water stability of coral soil,and the internal force of the concrete slab is less than the tensile strength and shear strength of the designed C28/35 concrete surface layer,which meets the application requirements,and greatly reduces the project cost.The research results can provide reference for similar projects.