Using characteristic distribution pattern of forward-scattering Müller matrix belonging to ship wakes (FSMMBSW), relations among matrix element, bubble number density and bubble radius are discussed based on Mie scattering theory by use of single-scattering model, in which calculated results show that, m2 and m4 elements have relatively strong shocks for a single bubble with scattering angle ranging from 0 to 90\O, and amplitudes of these shocks increase with rising radius. M11 and M44 of FSMMBSW for bubbles have no clear change with different azimuths. Distributions of elements changing with different azimuths are in accordance with the law of sine shocks, and elements of FSMMBSW decay with polar radius exponentially; M11, M44 and their amplitudes change with different azimuths, increase with radius rising. Maximums of the elements occur at bubble number density of 108 m-3. Characteristics between elements are opposite with different number densities around sides. Besides intensity, information of phase reversal with bubble radius as well as number density changing is reasonably contained in M12 and M13.