Due to its unique structural design, the tiltrotor aircraft exhibits severe aeroelastic coupling among the rotor, nacelle, and wing. Addressing the issue of tiltrotor whirl flutter, this study employs Hamiltonian theory to establish a coupled dynamic equation for the tiltrotor/nacelle/wing system. A coupled aeroelastic dynamic analysis model for the tiltrotor is developed, and modal characteristics of the tiltrotor wing are analyzed using an eigenvalue solution method. The computed results show good consistency with reference results, validating the effectiveness of the computational model. Building upon this foundation, the study further analyzes the impact of collective/pitch-flap coupling coefficients and hub precone angle on whirl flutter stability. The results indicate that as these coefficients increase, the stability of tiltrotor flutter decreases. These research findings hold significant implications for the dynamic design of tiltrotor aircraft.