Because the measurement accuracy of the diffuse radiation photoelectric sensor in the photoelectric insolation meter seriously affects the accuracy of the solar irradiance measurement， in order to reduce the scattering error，more accurate simulation of the diffuse radiation is needed for indoor calibration. Through the linear correlation analysis between the radiation attenuation rate and each meteorological factor in the day-by-day time scale， the daily horizontal solar scattering radiation model in Changchun area is obtained after multivariate linear regression fitting. The radiation attenuation caused by the scattering of water vapor and dust is simulated in the indoor verification system， and the indoor scattering environment simulation chamber is designed. The results show that the fitted values of the daily scattered radiation in the horizontal plane are well matched with the measured values. The measured values and fitted values are evenly distributed on both sides of the fitted line， and the correlation coefficient （R²） is above 0.8， indicating that the scattered radiation model has a good effect.