Abstract: A body-fitted orthogonal grid around complex configurations including wing,body,pylon and nacelle has been suc-cessfully generated by applying the multi-block grid technique and the method of solving elliptic and parabolic partial differential e-quations.The transonic flow field and aerodynamic characteristics of the advanced twin engine transport aircraft are also simulated numerically by using finite volume methods to solve the Euler equations with high efficiency,and the viscous effect of wing bound-ary layer is considered.Results of the calculation show that pylon and nacelle have significant effect on the supercritical wing aerody-namic characteristics.the numerical results are in good agreement with the experimental wing surface pressure distribution data.