Abstract: With the experimental data of buffeting force in tube bundles subjected to air-water two-phase flow, the characteristics of buffeting force associated with two-phase flow were determined, and the effect of mixture velocity and bubble size on buffeting force was analyzed. The results show that the buffeting force increases linearly with the interfacial velocity, mixture density and kinematical viscosity, and the buffeting force in the bubbly flow regime increases linearly with the bubble size. It is discovered that the dominant frequency of buffeting force of two phase flow is correlative with the bubble number rate. Based on the characteristics of buffeting force, a normalized expression for the buffeting force is given for engineering application. A better normalized effect is obtained with this expression.