An analytical model of coaxial articulated rotor helicopter ground resonance was established, and the modalcharacteristics of the ground resonance was got with method of eigenvalue analysis. The distance between upper and lowerrotor, rotor lag hinge offset, lag rigidity and lag damping ratio of rotor design parameters were analyzed on the influence ofcoaxial helicopter dynamic stability. The results showed that reducing of the distance between upper and lower rotor, thedynamic stability of the system improved, and dynamic instability center away from operating speed; increasing of lag rigid.ity and rotor lag hinge offset, the dynamic stability of the system improved, and dynamic instability center away from oper.ating speed; increasing of lag damping ratio, the dynamic stability of system improved, but dynamic instability center a lit.tle closer to operating speed.