After the operation of the Nuozhadu Reservoir, the largest cascade reservoir along the Lancang River, the original vegetation in the water-level-fluctuating zone (WLFZ) was inundated and extinguished, resulting in large areas of secondary bare ground and severe soil erosion. Ecological restoration of vegetation in the WLFZ is necessary but lacking basic data support and scientific reference. In this paper, based on 3S technology supported by light drones and combined with field research, a neural network model, spatial superposition analysis, landscape pattern index and typical correlation analysis were used to extract the vegetation classification map and topographic data of the typical WLFZ of the Nuozadu Reservoir in July 2020, and to intuitively and quantitatively analyze the native species composition, area, coverage, distribution characteristics along the terrain, landscape spatial pattern and their topographic attribution in the study area. The results showed that the vegetation coverage of the study area reached 74.13%, covering 18 species of plants, with the number of species only 18.9% of that before the construction of the reservoir. Only Chromolaena odorata (Chr) survived in the native plants. The species composition tended to be simple, with annual and perennial herbs dominating, accounting for 55.56% and 33.33% respectively, with Asteraceae as the dominant family, Xanthium sibiricum (Xan), Cynodon dactylon (Cyn), Eleusine indica (Ele) and Ageratum conyzoides (Age) were the dominant species, accounting for 47.41%, 29.39%, 9.37% and 4.56% respectively, and could be used as alternative species for restoration. The vegetation in the WLFZ was affected by topographic factors in the following order:elevation>surface fluctuation>nearest water distance>slope>topographic humidity index>slope direction. The dominant plants in the study area were all aggregated distributed, with patches of Xan and Cyn dominating the lower-middle part and upper part of the WLFZ respectively, with Xan and Cyn showing much greater patch dominance, connectivity and shape complexity than Ele and Age, showing a stronger potential for survival. Xan was well covered in the 0-1.26 m section of surface fluctuation, and Cyn and Ele were well covered in the 0.78-2.07 m section of surface fluctuation. When the surface fluctuation was >2.07 m, the vegetation growth was difficult. The degree of fragmentation of the vegetation landscape pattern and the complexity of the patch shape were positively and negatively correlated with the surface fluctuation respectively, i.e. the greater the surface fluctuation led to the more fragmented and simple shape of the vegetation landscape pattern, which in turn led to a reduction in the viability of the population.