Abstract: The measurement principle of a transient hot-plane method was introduced to improve the service temperature of the method. The sample temperature distribution of a filmless plane heat source during heating process was simulated based on the finite element method. The experimental apparatus was established and practical measurements for the thermal conductivity and thermal diffusivity of materials were made at an environment temperature of 27 to 829℃. The results show that the transient hot-plane method is effective for measuring the thermal conductivity of materials in a high temperature environment, which is applicable to actual measurements.