Vegetation plays an irreplaceable important role in soil improvement, sand fixing, environment purifying, climate adjusting and human survival etc. Therefore, the study of vegetation is indispensable for the research on the ecological environment of the earth. The more and more mature thermal infrared detection technology can provide a more rapid and effective means for the vegetation research. By measuring the brightness temperature of the typical ground vegetation in Cangchun city, Jilin Province, the thermal radiation properties of different kinds of vegetation are obtained. The thermal radiation properties of different kinds of vegetation are studied in different wavebands and time phases at different angles. The result shows that the brightness temperature of vegetation is affected by the kind of vegetation largely, by the waveband less, by the measurement time obviously and by the detection angle greatly. It provides an important basis for more accurate recognition and classification of vegetation.