Abstract: In the numerical simulation calculation of small solar chimney（SC）,different flow modes（laminar flow,turbulence or transition）are selected to obtain different calculation results. In this paper,ray tracing and environmental crosswind simulation are used to numerically simulate different flow models,and the calculated results and test data are compared and analyzed. The results show that the intensity of fluid turbulence and the degree of ambient crosswind disturbance under the transition model at different times are smaller than those of laminar flow model and turbulence model,so it is more accurate to use the transition model in calculation,which provides a reference for the model selection of small SC flow field simulation calculation.