Most of the former studies on characteristics of scattered light on large bubbles in water are based on Davis model, in which a bubble is regarded as an uncoated spherical object. However, most of the bubbles in water are coated with oil layer, which surely influences their scattering characteristics. We establish a simplified equation to calculate how a light beam is scattered when it enters a coated bubble. A two-dimensional curve,namely volume scattering function (VSF) is plotted, that models the angular distribution of scattered intensity by a coated bubble with a diameter far larger than wavelength of incident light. The curve reveals the far-field characteristics of light scattered by the coated bubble, as well as the main influence on scattering intensity. By comparing with VSF of uncoated bubble, we discuss the parameters that influence distribution of scattering light on a coated bubble, such as thickness of the oil layer, relative index of refraction and get that oil coating weakens the forward scattering of the coated bubble while strengthens the backward scattering.