Abstract: The pressure distribution on a circular cylinder surface in three surface roughness conditions was measured. The flow around the cylinder and aerodynamic force were studied. The results show that increasing surface roughness of cylinder makes a higher Reynolds number and thus it is effective to simulate supercritical flow around circular cylinder at a relatively low wind speed. It is concluded that increasing surface roughness is useful in wind tunnel load test simulating cylindrical structures in supercritical flow at relatively low Reynolds numbers.