In order to explore the effect of different dust weight on vegetation canopy spectrum, we selected Shanghai Normal university as the study area located in the center of Shanghai and determined the canopy spectral reflectance under different grades of foliar dust including Sophora japonica, Bauhinia, Photinia fraseri, Vinca etc using ASD FieldSpec 3. Then we weighed the foliar dust of corresponding species using electronic analytical balance in the laboratory and calculated dust catching of each plant. On this basis, we analyzed the influence of different foliar dust weight on canopy spectral characteristics of plants. After analyzing the different spectral curves, we got some conclusions. The spectral reflectance of plant canopy between 710～1 350 nm reduced as the foliar dust increasing and the difference among the three curves was large. The different dust weight impacting on the reflectance spectrum of vegetation was more complicated in 350～710 and 1 450～1 750 nm. The difference between the three curves was small in 350～710 and 1 450～1 750 nm bands but the ratio of difference was not small. The influence of foliar dust on canopy spectral of plants was not only related with the weight of dust but also related with species of plants. In the vicinity of the “green peak” and “red edge”, the slope of the plants reduced with the increasing of the amount of dust. The sensitivity of the spectral curves of different spieces or different wavelengths of the same plant to the dust was different. The foliar dust did not led to the phenomenon of red edge displacement, but it weakened the “twin peaks” phenomenon of the first derivative of red edge. The difference between “peak” and “secondary peak” reduced as the dust weight increasing and red edge was located in 719 nm. Finding the relationship between foliar dust or different dust weight and vegetation canopy spectrum will be of great significance for hyperspectral remote sensing application in this field.