A mathematical model of a simply supported tube with clearance restriction in an otherwise rigid rotated triangular tube array subjected to two-phase flow was established in this study. The nonlinear vibration responses of the tube bundles system were calculated, and the fatigue damage evaluation were carried. The relationships between the fatigue damage and collision behavior are obtained. The numerical results indicated that the reduced velocity has an obvious effect on the dominant frequency, the collision frequency, and the equilibrium position the system. The nonlinear dynamic characteristics of simply supported tube with clearance restriction in an otherwise rigid rotated triangular tube array may essentially determine the fatigue damage results.