The 3D green quantity can reflect urban vegetation’s spatial distribution characteristics and provide scientific data support for urban greening management. This paper used the 2014 GF-2 remote sensing image of Minhang District, Shanghai, and utilized the object-oriented supervised classification method to classify the vegetation types. By calculating the vegetation index, extracting texture information, and establishing a multiple linear regression model, the 3D green quantity of the vegetation in the study area was inverted. The results showed that the total 3D green quantity of the urban forest is 0.04 km3, and the average 3D green volume per unit area is 1073.65 m3/hm2. Cinnamomum camphora community accounted for 58.50% of the forest types in the study area, which was the primary vegetation community. The vegetation index indicated that the vegetation cover is dense in the north and south of the region and that in the central part is lower.