Abstract: Test techniques with boundary layer transition have been investigated to meet the high speed wind tunnel test requirements of aircraft models with high aspect ratio wings. Investigation results indicate that, compared with the grit type carborundum, the cylindrical transition trips have an advantage of more repeatable and controlled pattern, and thus are used in high speed wind tunnel tests of aircraft models with high aspect ratio wings. Not only drag characteristics, but also lift and pitching moment are all affected by boundary layer transition for aircraft with high aspect ratio wings. Thus, it is suggested that, in order to improve the test accuracy, testing in wind tunnels of low Reynolds numbers be conducted with fixed transition.