Abstract: Mie theory is a powerful tool for calculating the scattering properties of spherical bubbles, but it can not give much insight into the physical scattering process (such as reflection, refraction and diffraction) as the geometrical model and Debye model do. Calculation with the geometricaloptics theory or Debyeseries expansion of the Mie amplitude can help us to understand the physical scattering mechanisms. In this paper, the scattering patterns of large spherical bubbles in water are calculated by both geometricaloptics model and the Debye model. A detailed comparison between the geometricaloptics model and Debye model is presented. The analysis result shows that the result from the geometricaloptics approach agrees well with those obtained by Debyemodel for the perpendicular polarized component when the size of the bubbles becomes large enough. However, there is large variance between the two calculations in the scattering region of 45°～90° for the parallel polarized component.