In order to study the influence of air supply velocity on cabin thermal comfort,improve the problem of poor cabin comfort and energy saving effect caused by constant air supply velocity of bridge load air conditioning, the cabin simulation threedimensional (3D) model based Boeing 737 aircraft cabin and human body is built by using the method of Computational Fluid Dynamics(CFD). The Integrated Predicted Mean Vote-Predicted Percentage of Dissatisfied people (IPMV-PPD) was used as the thermal comfort index, the wind speed, temperature and IPMV,PPD values of each sampling point were collected, and then the relationship between the air supply velocity and the average value of the thermal comfort index IPMV and PPD was obtained by Gaussian fitting. So the optimal air supply velocity range is obtained,which meet the thermal comfort requirement and provide theoretical basis for energysaving of bridge load air conditioning.