To investigate the external drag characteristics of wing-mounted nacelles, this study focuses on a large transport aircraft. A full three-dimensional simulation model was established by employing a zonal hybrid grid technique to process the internal flow channel of the power unit and the nacelle-airframe combination. Numerical simulations were conducted using the Reynolds-averaged Navier-Stokes (RANS) turbulence model under varying flight Mach numbers, angles of attack, and engine operating conditions. Wind tunnel tests were performed on the same configuration, and the validity of the computational fluid dynamics (CFD) results was verified by comparing the surface static pressure coefficient distributions on the nacelle. A zonal correction method was applied to calibrate the nacelle pressure drag in the CFD results, using static pressure coefficients obtained from a reference test state as the baseline. The derived correction coefficients were subsequently extended to other simulated conditions. Compared with uncorrected results, the relative errors between the corrected CFD predictions and wind tunnel-measured external nacelle drag were reduced by approximately 3%–15%, demonstrating the effectiveness of the proposed calibration method. This work lays a foundation for correlating CFD simulations with wind tunnel experiments in aerodynamic studies.