The invention relates to an implementation method of a model for predicting propagation of light in biological tissues, which comprises the following steps: by using a self-adapting multigrid model, according to the error of the solving result on the coarse grid, dissecting the coarse grid in a self-adapting way to obtain a fine grid; and carrying out smoothing iteration on the fine grid by usingthe full V circulation on the multiple grid to eliminate high-frequency remnant quantity, restricting the secondary result to the coarse grid to correct the remnant quantity, and prolongating to the fine grid to carry out the smoothing treatment until achieving the claimed accuracy. The invention effectively reduces the calculation cost due to the increase of the grid dimensionality, increases the convergence rate, and enhances the calculation accuracy since the low-frequency error is directly solved. The invention can effectively simulate the process that photons are emitted in vivo and achieve the surface through multiple scattering in an optical molecular image.