To investigate the influence of inhomogeneous aerosol field on radiative transfer process in near-infrared band, representative inhomogeneous aerosol fields are constructed, and the radiance, polarized radiance and flux density of the diffuse light are simulated by the radiative transfer model spectral harmonics discrete ordinary method (SHDOM) for different aerosol fields. In addition, the simulation error caused by taking the inhomogeneous aerosol fields as plane-parallel ones is analyzed numerically as well. Simulation results indicate that, inhomogeneous distribution of the aerosol particles has significant influence on the radiative transfer, and the simulation error of the polarized radiance caused by the inhomogeneity of the aerosol field is higher than that of radiance, where the simulation error of radiance and polarized radiance can reach 9.8% and 80%, respectively. Horizontal inhomogeneity of the aerosol field has a great influence on the simulation error distribution of radiance and polarized radiance, while the vertical inhomogeneity has a more notable effect on the radiative transfer process and has no significant influence on the distribution. As the aerosol concentration increases, simulation error caused by the inhomogeneity of aerosol fields gradually decreases. The simulation error of flux density is smaller than that of radiance and polarized radiance in magnitude, which is less than 5% for most case. It is also found that the variation of the simulation error with height shows specific distribution characteristics. This work will be helpful for both the determination of applicable scope of the plane-parallel atmospheric radiative transfer models and the estimation of error caused by the aerosol field inhomogeneity in remote sensing process.