The invention discloses thermal conductivity measuring device and method. The heat conductivity measuring device comprises a thermal probe, a thermoelectric couple, a collector and a data processor, wherein the thermal probe is inserted into a sample to be measured for thermal conductivity measurement; the thermoelectric couple is used for measuring the wall surface temperature of the thermal probe; the collector is used for collecting the wall surface temperature measured by the thermoelectric couple and corresponding measuring time; and the data processor is used for combining a thermal conduction differential equation expressing wall surface temperature increase with the thermal conductivity of the sample to be measured, which is obtained by inversely processing the wall surface temperature and the corresponding measuring time. The invention sufficiently considers the thermal probe capacity, the thermal contact resistance between the thermal probe and the sample to be measured, andthe like, thereby greatly enhancing the measurement accuracy of parameters, i.e. thermal conductivity and the like.