Abstract: From the Mie scattering theory, using single bubble scattering model, the forward scattering characteristics and the illumination distribution of forward scattering which around the optical axis of the laser were studied. With the wavelength of 632.8 nm, the illumination of scattering laser beam was measured and analyzed in different media under varied pressures. Research results indicate that, the forward scattering light beam of the laser mainly distribute in the range of 0.588 around the optical axis. Along the laser optical axis, illumination is axisymmetric, and the cross-sectional distribution is Gaussian distribution. Considering the scattering of water body itself, the ratio forward scattering illumination is probably accounted 35%, 45% and 55% of the total under the pressures of 0.006 MPa, 0.008 MPa and 0.010 MPa. The results show that the forward scattering light of the laser and pressure were inversely proportional whether the water self-scattering is calculated or not.