Abstract: To optimize combustion efficiency, the structural characteristics of the zoned and staged double P-type gas-fired radiant tube were improved. The corresponding experimental and numerical studies were performed on the new radiant tube and the results show that deviations in the monitoring parameters are less than 1%, except for a NO_x concentration of 11.6%, which proves the reliability of the model. On this basis, the gas and wall temperatures were compared by changing the nozzle position and structure parameters of main and branch pipes. The results show that as the nozzle position moves outward, the highest value of the surface temperature of the radiant tube gradually decreases and the minimum value of the wall temperature gradually increases. When the nozzle of the branch pipe locates at the intersection of the tee and branch pipes, it helps to reduce the impact of the high temperature gas on the pipe wall, improve the uniformity of the branch radial temperature, and prolong the service life of the radiation tube. When the nozzle is fully premixed, the temperature difference is minimized. When the pipe nozzle is asymmetric, the difference in the wall temperatures is minimized and the thermal combustion efficiency is the highest.