A large number of bacteria inhabit in Microcystis phycosphere. They affect the growth and colony maintenance of Microcystis, and play important roles in the development and elimination of Microcystis blooms. Bacteria accompany the formation and disaggregation of Microcystis aeruginosa colonies during their growth, but changes in bacterial communities during the process were still unclear. In this study, Microcystis colony development and bacterial community variation in colonial Microcystis strains isolated from Lake Taihu were monitored during cultivation at different temperatures. The experimental results showed that the growth pattern of this colonial Microcystis strain to varying temperatures from 15 ℃ to 30 ℃ was different, the higher the temperature the faster the colonies disaggregate, and the shorter the time for Microcystis aeruginosa colonies to reach the peak. During the growth process of D2 colonies, the dominant bacterial communities associated with Microcystis colonies of ＞20 μm shifted from Pseudomonadales to Sphingomonadales; The dominant bacterial communities associated with unicellular-small Microcystis colonies of 3-20 μm changed from Pseudomonadales to Cytophagales, which were similar to those in the free-living bacterial community. On genus level, Limnobacter were dominated only in the free-living bacterial community; Roseococcus were dominated only in Microcystis colonies of ＞20 μm; Porphyrobacter were dominated in free-living bacterial community and unicellular-small Microcystis colonies of 3-20 μm; and Mesorhizobium were dominated in unicellular-small Microcystis colonies of 3-20 μm and Microcystis colonies of ＞20 μm. Venn diagrams and specificity-occupancy (SPEC-OCU) plots of bacterial communities at different particle sizes and temperatures revealed that some exclusive and specialized species only appeared at 15 ℃, OTU669 (Methylobacteriaceae), OTU722 (Brevundimonas sp.) and OTU682 (Pseudoxanthobacter sp.) were specialized species of the Microcystis colonies of ＞20 μm at all temperatures. Network analyses revealed that bacterial communities in Microcystis colonies of ＞20 μm had the most critical nodes. These results revealed variation patterns in bacterial community composition of different particle sizes during the growth process of colonial Microcystis aeruginosa. This study would contribute to a better understanding of the role of bacterial communities in Microcystis blooms.