The safe operation of an overhead transmission line directly affects the reliability of power supply. The low-wind-pressure conductor is a new type which reduces the wind pressure of a transmission line under strong winds. It is of great significance to the safe operation of overhead transmission lines. The temperature of the conductor is the main factor limiting the transmission capacity of the line. For a more comprehensive evaluation, a multi physical field coupling module of electromagnetic fluid solid heat transfer is simulated by the finite element method, and the model of conductor and surrounding air domain is built. Considering the air gap and skin effect in the strand and the influence of sunshine heat generation on the radial temperature distribution of the conductor, the heat source is divided by layer. The temperature characteristics of the low wind pressure conductor and conventional conductor under natural convection and forced convection are compared and analyzed. The results show that the low-wind-pressure structure of the conductor makes the radial temperature difference much smaller than that of the conventional conductor under the same working conditions, and is basically not affected by the convection conditions. The increase of aluminum cross-sectional area reduces the heating under the same current carrying capacity, and the overall temperature is lower than that of a conventional conductor. This work is supported by the National Natural Science Foundation of China (No. 52005315).