The local heating method is a method for measuring thermal conductivity of nonmetallic materials under steady Condition. A small heater-probe is employed to heat the sample surface locally, then the thermal conductivity can be determined according to the heat flux injected and the rise of the local surface temperature. The theory of the method is expounded. The construction of the heater-probe and experimental results are also given in this paper, It is found that this method can be used to take in-situ and nondestructive measurement of the thermal conductivities of materials. The existing data are fully in agreement with those reported in the literatures.