Abstract: Pneumatic conveying system is a crucial component of cotton picker, with air distribution box serving as a key element within this system．Air distribution box distributes air volume at fan outlet to picking device of cotton picker, and structure of air distribution box plays an important role in air volume distribution．Two different structural models of air distribution box s were developed．ANSYS software was utilized to conduct numerical simulations of variations in wind speed and wind pressure within air distribution box with different structures．Velocity vector cloud image, wind pressure cloud image, and average wind speed at each outlet of air distribution box were analyzed．Results indicated that, under premise of meeting wind speed requirements, structure of model II was more reasonable．