Abstract: There are many engineering structures with circular sections. At regular wind speed, the Reynolds number of these structures can reach 10⁷ or more which falls into high supercritical Reynolds number region. However, researches on circular cylinder in this region are few. Based on this situation, the wind load of a single circular cylinder of 5 meters in diameter is studied by numerical calculation. The computational domain, number of circumjacent grid, height of the first normal layer grid and computational time step are examined. The drag coefficient and the flow field distribution around the circular cylinder are obtained.