It is essential to understand the structure and content of HDF-EOS data,as well as the calculation method of physical quantities,for applications of MODIS.The HDF-EOS is developed by NASA to manage and distribute EOS data,being set up as the standards of EOS data and information systems.MODIS 1B products adopt the HDF-EOS format,including the calibrated data with the resolutions being 250 m,500 m and 1000 m,as well as the data from onboard calibrators and other data.There are 36 channels in daytime and 17 channels in nighttime.The detection signals are compressed to a scale into 16-bits integers,and the reflectance and radiance can be calculated by the scales and the offsets.