Li4SiO4 is the tritium breeder material for helium cooled solid breeder blanket concept.The thermal properties of ceramic pebble beds provide important support for the design of solid breeder test blanket module(TBM).A kind of device for the measurements of the effective thermal conductivity of a packed ceramic pebble bed by steady state method was developed and the effective thermal conductivity of a non-compressed Li4SiO4 pebble bed at temperatures ranging from 300 ℃ to 640 ℃ were measured in this study.The packing factor was about 59.7%for the single size pebble bed and helium at atmospheric pressure was used as a filling gas.The experimental results showed that the effective thermal conductivity increased with the increase of the average bed temperature and the effective thermal conductivity had an approximate linear relationship with the temperature.