Abstract: A numerical model of atmospheric optical refractive index structure parameter is presented. The input data for this model consisted of date，time，latitude and longitude，temperature，humidity，windspeed，roughness length，soil parameter，and cloud parameter,24h forecasts of the time variation of refractive index structure parameter near the surface will be produced. Comparison of measured and modeled results indicated that refractire index structure parameter both monthly and daily averaged can give consistent results. Comparison of total downward radiative flux modeled and measured is generally quite satisfactory．