Abstract: A high breeding ratio blanket (HBRB) was designed with porous U-10Zr alloy as neutron multiplier, Li₄SiO₄ pebble bed as tritium breeder, RAFM steel as structure material respectively. Detailed internal structure was developed with consideration of fabrication procedure, flow rate distribution and neutron performance. The tritium breeding ratio (TBR) and distribution of heat deposition were calculated, and the thermal hydraulic analyses of the HBRB combining with results of neutronics calculation were also carried out. The results show that the TBR is high enough and the neutronics performance is stable. The coolant flow rate distribution and pressure drop are reasonable. The maximum blanket component temperature and thermal stress are lower than critical values.