In the sintering process, the non-powered hot air sintering gas can be used to heat the material surface of the trolley and reduce the consumption of sintering fuel, but due to the characteristics of the pipeline structure, the gas distribution will be unevenly distributed, so the optimal design of the gas distribution pipeline structure can effectively avoid the problem of uneven gas distribution and improve the heating uniformity of the material surface of the trolley. In this study, the non-powered hot air sintering device of a sintering plant is taken as the research object, and the effects of the structure of the main pipeline of non-powered hot air sintering, primary distribution pipeline and secondary distribution pipeline on the airflow uniformity are investigated by computational fluid dynamics method. The results show that after the original design hot air enters the gas distribution pipeline, the variance of the hot air velocity in the primary distribution pipeline is 0.257, and the variance of the hot air velocity in the secondary distribution pipeline is 0.696, and the uniformity of the air flow is poor. In view of the uneven distribution of the airflow of the original structure, the variance of the primary distribution hot air velocity is 0.0379 and the variance of the secondary distribution hot air velocity is 0.144, which is 85.3% and 79.3% higher than that of the original structure, respectively, so that the hot air can enter the material surface evenly, eliminating the problem of uneven heating of the hot air on the material surface, which is conducive to the energy-saving operation of sintering. The results can provide a reference for the design of non-powered hot air pipeline in the sintering process.