In single bubble sonoluminescence (SBSL), the forward Mie scattering signal of the bubble, which is waved due to the interference between the scattered light components, provides a scale for measuring the change of the bubble radius. The unit of the scale is decided by the scattered angle θ, the optical wavelength λ, and the relative refraction index n of the fluid; and the scale marks are the peaks and valleys of forward scattered light, which correspond to specific radius values. The forward Mie scattering method has been applied in measurement of the R(t) curve, especially the maximum radius value Rmax, and further in the fit of the equilibrium radius R0 of bubble in SBSL, and is proved to be a feasible and convenient technique in the study of the bubble dynamics in SBSL.