The difference in the frequency of rigid-body mode and the elastic mode of modern large passenger aircraft is becoming smaller， and the problem of rigid-elastic coupling during maneuvering is becoming increasingly apparent. Traditional flight dynamics simulation with six degrees of freedom cannot simulate this rigid-elastic coupling process， which is unfavorable for the optimization of control laws or the development of flight training simulators. By analyzing the basic motion characteristics of large passenger aircraft， we use the mean axis system method to extend the traditional flight dynamics equation， and construct a rigid-elastic coupling flight dynamics simulation model for large passenger aircraft， significantly simplifying the analysis process while inheriting the original simulation system. Meanwhile， the rigid-elastic coupling simulation model is used to analyze the typical rigid-elastic coupling problem of large passenger aircraft under pitch and roll maneuvers， with comparison with flight test results to verify the accuracy of the model. The model is then adopted to study the rigid-elastic coupling characteristics of large passenger aircraft under typical pitch and roll maneuvers， as well as the impact characteristics of rigid-elastic coupling on dynamic stability and elastic modes.