The method solved three-dimensional compressible RANS equations on a point-to-point multi-block structured grid was employed in this paper. Firstly, the DLR-F11 standard model used in the 2nd AIAA high lift prediction workshop (HiLiftPW-Ⅱ) was simulated to validate the reliability of the research method, the results showed that the computational predictions agreed well with experimental, so that the research method could be employed to predict flow field of a complex civil transport aircraft configuration with high lift device. Secondly, we investigated the effects of engine failure on longitudinal aerodynamic characteristics of a civil transport aircraft. The results shown that engine failure not only made drag coefficient increase obviously, but also affected lift coefficient, pitching moment and stall characteristics adversely.