Flows past a wide-body aircraft operated at cruise, drag divergence and dive Mach numbers are transonic flows. When the aircraft model is tested in a transonic wind tunnel, strong shock wave may be induced due to the tunnel wall, which will incur the complex wall interference as a strong nonlinear coupling phenomenon. In order to investigate the wall interference to the standard model of a wide-body aircraft mounted in the FL-26 wind tunnel, a numerical simulation method based on a porous wall model was developed, and employed to research the interaction between the wall and the model at Mach numbers ranging from 0.8 to 0.92. Compared with the wall pressure information method, results obtained with the porous wall model indicate that the effect of the porous wall on the curve of lift coefficient can be captured better without measured data, but larger effect on the drag coefficient is produced.