Abstract: Backfill materials in disposal tunnels are important parts of engineering barrier systems, and the engineering design is closely related to the long-term safety of repositories. Based on investigation of design requirements on backfill materials in Sweden which has advanced geological disposal technology, including backfill material composition, properties of backfill blocks and pellets (water content, geometry, density) and installation schemes. The concept of geological disposal of high-level radioactive wastes in China was put forward, the composition of the backfill material was Gaomiaozi bentonite and sand, the design requirements on backfill blocks including geometric states and dry densities were proposed. The research could provide reference to the related experimental research of backfill materials for geological disposal repositories of high-level radioactive wastes in China.