A simulative model with Monte Carlo method is established based on Fournier-Forand and Henyey-Greenstein volume scattering functions, by which propagation characteristics of optical pulse underwater can be analyzed. By using this model, the influence of scattering particles′ relative refractive index and size distribution on optical pulse propagation in water is analyzed. The results show that, with the increase of the relative refractive index of scattering particles and small scattering particles′ relative quantity, the width of optical pulse is broadened more evidently in time domain, the forward scattering becomes weaker with a more disperse space distribution and arrival angles′ distribution. Compared with traditional simulative models, the method presented is more effective.