Abstract：Based on theory of linear heat-source，the basic principle of distributed fiber optical technology for thermal conductivity measurement is described. The measurement process，method and apparatus are introduced. Test model is also built；and the thermal conductivities of three types of geomaterials with different water contents are measured by using distributed fiber optical technology. By means of analyzing test data，the relationship between fiber optical temperature and time is studied. Temperature curve is made up of two segments，i. e. swift growth and gradual uniform growth segments. At uniform growth segment，there is a well logarithm relationship between temperature and time，which approves the feasibility of this method. Through analyzing the effect of heating power on thermal conductivity，the effect of heating power on thermal conductivity can be ignored when the heating power is in the range of this test. Through research of water content¢s effect on thermal conductivity，it is found that water content has dramatic effect on thermal conductivity. Thermal conductivity increases with the increment of water content，but the increasing rates of different media are different. At last，this method is discussed.
