In order to accurately simulate the transition in aeronautical engineering, the low speed flat plate data was adopted for the calibration of γ－Re_θ transition model based on high-order WCNS (weighted compact nonlinear scheme) on the platform of high-order numerical wind tunnel. Based on the calibrated transition model, the flow over the low speed airfoil was investigated. Comparison between the calculated results and the experiment data indicates that the γ－Re_θ transition model based on WCNS can predict the location of nature transition, bypass transition or separation transition very well and has low mesh sensitivity; only the transition model can calculate the drag coefficient accurately within a moderate Reynolds number range where the length of the laminar flow region is comparable to that of the turbulent flow region.