The measurement accuracy of T-TDR sensor was improved via studying the heat conduction process and optimizing the embedded point of the thermocouple nodes. Using 2-D heat transfer equation in the soil, the initial boundary value of the Heat Transfer of the T-TDR probe was analyzed numerically. Then the relationship between the thermal field of T-TDR with time, thermal conductivity and capacity of soil was established. Furthermore, the dynamic process of heat transfer and spatial thermal distribution of T-TDR at different environment temperature, conductivity and volumetric heat capacity were simulated. The results showed that the optimal positions of the thermocouple node on both sides were on the probe midpoint at 2 mm thermocouple junction of the sensor terminal direction distance. This was the most sensitive point to the radiant heat of the intermediate probe. 