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The grid inventory-based approach is helpful for diagnosing vegetation properties of a given region, and provides support to explore the methods of vegetation classification. In this study, Dajinshan Island in Shanghai City was selected to conduct vegetation classification and vegetation mapping according to the methods of Tabulation and Two-Way Indicator Species Analysis. We divided this island into 140 regular grids（40 m × 40 m） based on an unmanned aerial vehicle image, and then surveyed community composition by using the Braun-Blanquet method and quadrat-based census across the grids. Under the newly revised three-level vegetation classification system, the first level of classification（i.e., vegetation type） included deciduous broad-leaved forest, evergreen and deciduous broad-leaved mixed forest, evergreen broad-leaved forest, deciduous broad-leaved shrubland, evergreen and deciduous broad-leaved mixed shrubland, evergreen broad-leaved shrubland, and grassland. According to the dominant species and floristic characteristics, the second level of classification included 15 types of associations or communities. The third level included 22 types of communities based on physiognomy and community age. These results indicate that Dajinshan Island is not only a species-richest region in Shanghai, but also possesses the most typical and diverse natural or semi-nature forest communities across islands in East China. In terms of vegetation status, zonal forest communities develop to the middle and late successional stages, but a few secondary vegetation still stop in the early successional stage, which encounter to the ecological problems such as development stagnation caused by monkey disturbance. With respect to the vegetation classification methods, the grid inventory-based technique can fully reveal the phenomena of intermittent and transitional communities in the continuity of flora. [ABSTRACT FROM AUTHOR]