In order to investigate the wind load distribution and the aerodynamic mechanism on irregular membrane structures, computational fluid dynamics (CFD) methods were employed to numerically simulate the wind loads acting on the surface of a large-span irregular membrane roof structure of a large-scale complex building. The simulation was performed using the OpenFOAM platform. The distribution of wind pressure and the shape factor on the membrane surface were analyzed, and the impact of grid density on the simulation results was also examined. Additionally, the aerodynamic effects of the wind field on the wind loads were further explored by examining the wind speed distribution. The results indicate that the grid density affects the accuracy of the numerical simulation, with higher grid densities yielding more precise results, but at the cost of increased computational load and reduced efficiency. The membrane surface is primarily subject to negative pressure, with the maximum wind loads occurring at the corners, local bends, and areas of surface distortion. The use of a concave arc-shaped slope at the outer edge of the membrane and the incorporation of concave forms at regions of high wind pressure can effectively reduce the wind loads.