Abstract: So far, gas hydrates not only have been explored in marine and frozen areas of China, but also have been sampled successfully. The thermal conductivity of sediments with gas hydrates is a key parameter for estimating the resource and designing a proper exploitation plan. Restricted to the stable conditions for hydrates and their measurement technique, much more work need to be done on the thermal conductivity investigation of hydrates. In this paper, a description of the measurement technique of the thermal conductivity and saturation of gas hydrates formed in marine sediment is given. Marine sediment collected from the Shenhu area of the South China Sea was taken as the porous media. The methane hydrates in them were synthesized under the conditions of 7.8 MPa pressure and 2℃ temperature. The thermal conductivity and saturation were measured by thermal pulse probe technique coupled with time domain reflection method. Based on the results, when the hydrate saturation changed from 0 to 49%, the thermal conductivity appeared to be initially increase and then decrease. It was deduced that the relationship between thermal conductivity and saturation was controlled by the hydrate filling pattern. In this experiment, gas hydrates priority selection in particle void nucleation and growth, and gradually cement with sediments.