Abstract: Sound scattering characteristics of a single bubble with viscoelastic shell are studied using the linear theory. And the multiple scattering characteristics of ultrasound contrast agents are calculated by the WT method. Firstly, a physical model of sound scattering of this bubble is set up. Combining wave equations in and out of shell and boundary conditions, we deduced the scattering matrix and then the scattering coefficients. In addition, in numerical calculations, we take reduced scattering cross sections as measurements for sound scattering characteristics of the single bubble; and then the sound dispersion curves and the attenuation coefficient curves for multiple scattering of bubbles in water. The numerical results show that as the value of elastic parameter of the layer μ_e increases, both the resonant frequency and the resonant scattering amplitude increase; The resonant scattering amplitude decreases as the value of the viscous parameter of the layer μ_v increases; And usually, another two parameters of the layer, λ_e and λ_v, do not affect the sound scattering characteristics of the bubble.