Abstract: Theoretical studies on the dynamic interactions between multi-bubbles is a key topic for better understanding the physical mechanisms underlying clinical applications of Ultrasound Contrast Agents(UCAs).In the present work,a2-D axisymmetric Finite Element Model(FEM) was developed to investigate the bubble-bubble interactions for UCAs in an infinite fluidic environment.The impacts of acoustic driving parameters and the bubble size on the bubble interaction tendency were discussed,as well as the influences of bubble shell mechanical parameters.In addition,the temporal evolution of the bubbles' radii,the distance between bubbles' center,and the distribution of the velocity field in the surrounding fluid were also investigated based on FEM simulations.The results indicated that,for the interacting bubbles,the overall translational tendency should be dominated by the relationship between the driving frequency and their resonance frequencies.For constant acoustic driving parameters,the bubble-bubble interactions could be regulated by adjusting the shell visco-elasticity coefficients of the bubbles.The current work should be beneficial for in-depth understanding of the theoretical fundamentals behind bubble-bubble interactions,which plays an important role in the controlling and optimization of UCA applications.