By means of measuring the surface reflectance by an automated test-site radiometer (ATR), measuring the atmospheric parameters by CE318 sun-photometer, and measuring the diffuser-to-globe factor by the diffuser-to-globe irradiance meter, a hyperspectral surface reflectance at the time of overpass is determined. Based on the reflectance-based method, absolute radiometric calibration experiments with in-site automated observation at visible to near-infrared bands 1-7 of the moderate resolution imaging spectroradiometer (MODIS)/Aqua and MODIS/Terra are performed. The results show that the relative deviation in top-of-atmosphere (TOA) spectral radiances is less than 4% obtained from the in-site automated observation radiometric calibration (AORC) method and from MODIS/Aqua and MODIS/Terra, which indicates the in-site AORC method is at the same level of calibration accuracy with the manual calibration methods. The feasibility of the in-site AORC method is testified.