To improve the simulation accuracy of scattering process in Monte Carlo radiative transfer model, a phase function sectional-weighted sampling method is put forward based on the characteristics of scattering phase functions, and its accuracy and feasibility are validated subsequently. Transmissivity and reflectivity of infrared laser (1.06 μm) in non-spherical sand aerosol are calculated using Monte Carlo method. Its results are compared with those of Henyey- Greenstein (H- G) phase function sampling method and phase function uniformly- sampling method. Simulation results show that, phase function sectional- weighted sampling method can improve the calculation accuracy of scattering angles obviously and reduce the sampling error of phase function. Compared with H-G phase function sampling method, transmissivity calculated by H-G formula is underestimated, while reflectivity calculated by H-G formula is overestimated, and the deviation of two methods increases with the increasing of propagation distance. Compared with phase function uniformly sampling method, the relative error of transmissivity increases with the propagation distance increasing, while the relative error of reflectivity changes oppositely.