Along with the development of economy and the living standard of residents, the discharge of industrial and agricultural wastewater and municipal domestic sewage has a serious impact on the water quality of the Pearl River Delta. Bacterial communities are important components in riverine ecosystem and play key roles in the degradation and transformation of various pollutions in river environment. Bacterioplanktonic community responds to changes in biotic and abiotic factors that are amplified during spring and summer these wet seasons, however, whether communities respond to environmental disturbance in dry seasons remains unknown. In this study, we collected surface water samples from the Pearl River Delta (112.18°E-113.51°E, 22.38°N-23.17°N) in November 2017 and January 2018, using high-throughput sequencing of 16S rDNA gene amplicons on the Illumina Miseq platform, to investigate the bacterioplanktonic community's composition and their environmental impact factors of the Pearl River Delta in winter. Total DNA was extracted from water samples by using DNA extraction kit (Magen Hipure Spil DNA Kit), and DNA concentration was determined by Qubit^® dsDNA HS Assay Kit. The targeted V3-V4 regions were amplified with the primers set (341f-CCTACGRRBGCASCAGKVRVGAA; 806r-GGACTACNVGGGTWTCTAATCC). The purified PCR products were sequenced on Illumina MiSeq (Illumina, San Diego, CA, USA) platform, and raw reads were screened by QⅡME (1.9.1), with the removal of chimeric sequences by UNCHIME. Operational taxonomic units (OTUs) were generated by Vsearch (1.9.6) with similarity at 97%, and aligned against reference database SILVA (http://www.arb-sliva.de). Αlpha diversity indices such as Shannon and Chao 1 index, and beta diversity based on Bray-Curtis difference coefficients were calculated in R (3.5.2) software (http://www.r-project.org) according to normalized OTU abundance. Non-metric multidimensional scaling (NMDS) was used to test communities dissimilarity, and analysis of similarities (ANOSIM) was used to test the similarity among different communities, by using vegan (2.5.2) package. Redundancy analysis (RDA) was used to analyze the relationship between bacterial community and environmental factors by using vegan (2.5.2) and ggplot2. Pearson correlation analysis was carried out with SPSS (19.0) statistical software (IBM Corporation, USA) to determine the relationship between environmental factors and the diversity of planktonic bacteria (Shannon index and Simpson index) and the abundance of specific bacteria. The results showed that Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria were abundant phyla in Pearl River Delta. γ- was the most abundant class among the communities, followed by Actinobacteria and α-Proteobacteria. The bacterioplanktonic community showed a relatively high diversity in the Pearl River Delta in winter, with no significant differences observed in bacterioplanktonic community's composition among all sampling sites. Pearson correlation analysis showed that the abundance of γ-Proteobacteria (P < 0.01) was positively correlated with temperature, while the diversity index was negatively correlated with PH (Shannon, < 0.007) and the abundance of α-Proteobacteria ( < 0.05) was negatively correlated with dissolved oxygen. RDA showed that temperature, pH were the main driving factors affecting the structure of bacterioplanktonic community. Temperature was identified as the main environmental factor affecting planktonic bacteria community. Previous studies shown the composition of bacterial community was driven more by temperature and the average cell size of planktonic bacteria community decreased with the increase of temperature. In addition, temperature was related to the diversity of estuarine ecosystems. Seasonal temperature variation was also considered to be the main variable affecting the dynamics of sediment bacterial community in the Pearl River Estuary. The pH was another major environmental factor affecting the structure and diversity of bacterial communities. pH was generally considered as an indicator of , in the study, negative correlation was observed between pH and Actinobacter (=0.016), which was consistent with the results of other studies. These results might provide fundamental information on bacterioplanktonic community composition and environmental factors in winter Pearl River Delta.