In order to explore the roles of gvpA copies and repeated sequences of gvpC, three Microcystis strains including M. aeruginosa FACHB910, M. aeruginosa FACHB930 and M. wesenbergii FACHB929 were used in this research. The length and diameter of gas vesicle, relative gas vesicle volume, appear pressure values, critical pressure values, cell turgor values were measured, and the correlations among these characters, gvpA copies, and repeated sequences of gvpC were analyzed. The results indicate that there are a significant positive linear correlation between gvpA copies and relative gas vesicle volume (r = 0.999); gvpA copies are negatively correlated with diameter of gas vesicle (r = -0.861). However, repeated sequences of gvpC have a significant positive correlation with diameter of gas vesicle (r = 0.911), and have significant negative correlations with relative gas vesicle volume, appear pressure values and critical pressure values, with the correlation coefficient of -0.851, - 0.999, - 0.928 respectively. So we presume that gvpA copies are probably the primary impact factor for relative gas vesicle volume. The diameter of gas vesicle is not only regulated by repeated sequences of gvpC, but also regulated by gvpA copies.