Unsteady state method has become the main means to measure the thermal properties of materials, and transient plane heat source method has the outstanding characteristics of short test time and obtaining multiple thermal parameters. In this paper, the measurement of thermal conductivity of thermal insulation materials by transient plane heat source method is theoretically analyzed and the measurement technology is studied. In this paper, the transient plane heat source method is derived to analyze the sensitivity of the thermal parameters of the ideal test model, and the possibility of estimation is determined according to the sensitivity of the parameters. The theoretical values of physical parameters are calculated according to the theoretical model to test the feasibility and accuracy of the improved Gauss method to estimate the parameters. Sensitivity analysis shows that the thermal storage coefficient of the material can be determined by the temperature rise curve of the heating surface, and the thermal conductivity and thermal diffusion coefficient inside the specimen can be estimated simultaneously by the temperature rise curve. Three-dimensional simulation verifies that the system meets the one-dimensional heat transfer assumption and the test sample meets the semi-infinite assumption in Z direction. The initial temperature inhomogeneity and ambient temperature are numerically simulated by ANSYS, and the simulation results are compared with the theoretical model by the parameter estimation method of thermal conductivity, so as to judge the error. The technical standard of thermal conductivity measurement of thermal insulation materials by transient plane heat source method is formulated, including method principle, device, heating power selection, sample size design and effective testing time.