Land surface net radiation is one of critical factors controlling variable land surface processes. Because of the contradiction between spatial resolution and temporal resolution, it is difficult to estimate the hourly or half-hourly surface net radiation with high spatial resolution (<;100m) using remote observation. A simple approach is proposed to retrieve the surface net radiation with high spatial resolution of 30m using multi-source remote sensing data (MODIS atmospheric products and ASTER surface products) under clear sky. The sinusoidal diurnal cycle function for land surface temperature is applied to the net radiation to estimate the hourly net radiation. The estimation results of instantaneous and hourly net radiation show good agreement with field meteorological datum.