This paper researches on the methodology for brightness temperature component classification and temporal variations of these component values by an in situ experiment dedicated to maize canopy brightness temperature distribution. Results show the number of components and their brightness temperature values vary with time of day and biomass density. Three components of vegetation

sunlit and shaded soil could be identified at midday during the measuring period. When the canopy is highly co-vered

vegetation’s brightness temperature has a wider range

and the components are difficult to be distinguished. The interpretation of these phenomena will be conceived in the further research.