Given the limitations of the traditional steady-state method, which involves setting a single heating temperature and neglecting heat dissipation from the sample’s sides, an improved experimental method for measuring the thermal conductivity of poor conductors has been developed. By introducing the convective heat transfer coefficient to correct the error caused by heat dissipation from the sample’s sides, and testing six different heating plate temperatures (60.0℃, 65.0℃, 70.0℃, 75.0℃, 80.0℃, 85.0℃), the results show that after correction using the convective heat transfer coefficient method, the relative error of the thermal conductivity for the six sets of experiments is significantly reduced, with a maximum decrease of 21%. It is determined that 80.0℃ is the optimal heating temperature, and the corrected thermal conductivity at this temperature is 0.271W·m-1·K-1, with a relative error as low as 3%. This provides an effective way to improve the measurement accuracy of thermal conductivity, which is expected to promote innovation in the teaching method of thermal conductivity experiments in university physics experiments and provide strong support for engineering practice.