Abstract：Characterization of cyanobacterial vertical movement is essential to understand the process of cyanobacteria bloom formation in shallow eutrophic lakes. Lake Taihu, which is characterized by frequent cyanobacterial blooms, was reasonably selected as our study area. Here, we characterize the vertical distribution characteristics of cyanobacteria under different turbulence intensity and colony sizes in Lake Taihu based on field experimental observations and one-dimensional advection movement model. The results show that the vertical distribution of cyanobacteria biomass was not uniform with cyanobacterial biomass peak appearing in the water surface or at a certain depth in the water column when the wind speed is low (wind speed< 3 m/s). For the bloom areas, the diameter of cyanobacteria colonies is larger than 75 μm and there is a small cyanobacterial biomass peak at a certain water depth. For non-bloom areas, cyanobacteria colonies with the diameter between 75~175 μm mainly appeared at the water depth of 1.2 m, while cyanobacteria colonies with the diameter ranging from 175 to 250 μm mainly concentrated in the water surface. The vertical movement simulations show that cyanobacteria colonies with diameters> 100 μm float demonstrated periodic floating and sinking movements with the changes of light. When the diameters< 100 μm, cyanobacteria gathered near the euphotic zone under the weak disturbance condition. The two types of characteristic peaks of the cyanobacteria biomass vertical profile at the water surface and at a certain water depth could be attributed to the differences in the movement characteristics of cyanobacteria colonies with varied particle sizes.