To evaluate the aerodynamic performance and flow field quality of the full-scale test cell for a domestic high-bypass-ratio civil aeroengine, this study is carried out targeting the practical engineering demands of dedicated test cells for domestic civil aeroengines, presenting distinct innovations and practical engineering value in aspects of modeling method, simulation refinement and engineering application. A full three?dimensional model is built to include key components such as the inlet tower, silencers, rectifying net, engine, ejector and exhaust tower. Refined structured grids are used , the standard k-ε turbulence model together with the wall function method is adopted to deal with turbulence and near-wall flow fields, and the SIMPLE algorithm is employed to solve the governing equations of the flow field. Velocity, pressure, temperature distributions and natural convection characteristics are analyzed. Results indicate that the test cell achieves an ejector coefficient of 1.97. The velocity non?uniformity at the section 6 meters upstream of the engine inlet is 29.05%, which satisfies applicable industrial specifications. The rectifying net greatly improves flow uniformity, reducing velocity non?uniformity by approximately 51.5%. The total pressure non?uniformity at the engine inlet is only 0.3%, indicating a low level of flow field distortion. Under natural convection, the internal flow speed is below 2 m/s, so the chimney effect has negligible impact. The test cell demonstrates rational aerodynamic design and excellent flow quality, which fully supports ground test and measurement requirements for the aeroengine.