As an important part of the urban ecosystem, urban vegetation creats huge ecological benefit, so reasonable classification of urban vegetation is in favor of urban construction and planning. Based on the typical vegetation classification of Changchun, it is found that the observation time, detection angle and band are the main factors affecting the brightness temperature of vegetation. The result shows that the brightness temperature of vegetations measured in different time periods is significantly different, so it can distinguish among different vegetations easily, especially at noon, it is the most conducive to identify the four vegetation types. The brightness temperature measured under different detection angles is also evidently different, and it can also achieve the effect of distinguishing among typical vegetations, especially the brightness temperature obtained under the 0° detection angle is the most favorable to the vegetation classification; but there is only subtle difference between brightness temperature of four channels, the brightness temperature obtained in different band ranges is difficult to distinguish among typical vegetations. The results can be used to provide important basis for the identification and classification of vegetation types.