To enhance the simulation accuracy of engine-level performance for aero-engines， a dual-spool mixed-flow turbofan engine is taken as the research object. Compressor inter-stage bleed air and turbine cooling air correction models are coupled into the engine-level performance simulation model to investigate their individual and combined effects on engine-level performance at different rotational speeds. The influence of coupled correction on engine throttling characteristics， altitude performance， and speed characteristics is also evaluated. The results indicate that significant differences exist in the simulated engine-level performance before and after coupling the compressor inter-stage bleed air and turbine cooling air correction models. At the relative rotational speed of high-pressure rotor Nhr=100%， the intake mass flow rate is increased by 3.8%， the surge margin of the high-pressure compressor is improved by 3.0%， the total outlet temperature of the combustion chamber is increased by 4.9%， the thrust is increased by 8.4%， and the specific fuel consumption is increased by 3.2%. Analysis of ground throttling characteristics， high-altitude cruise performance， and speed characteristics shows that the coupled correction does not alter the trends of engine-level performance variations. However， the performance after coupling is generally superior to that before coupling， with noticeable changes in magnitude. Therefore， in engine-level simulations， detailed consideration of compressor inter-stage bleed air and turbine cooling air corrections can make the simulation results more realistic and improve the accuracy of engine-level performance predictions.