Microalgae cellular contents are affected by various factors such as temperature, carbon dioxide, light intensity and so on. This study finds that microalgae cells were heterogeneous in terms of dielectric properties although their growth curves and nutrient consumption rates were similar. The shifting of dielectrophoresis direction between different culture generations of microalgae showed the gradual change of cell wall structure and compositions along the cultivation. Additionally, electrorotation spectra of microalgae cells behaving the same in dielectrophoresis were different. Two groups of cells were found in the log phase while the spectra of cells in the stationary phase were relatively uniform, indicating cellular contents were diverse in the log phase but similar in the stationary phase among individual cells. These results show that dielectrophoresis and electrorotation are informative and rapid technologies for analyzing microalgae cellular compositions with single cell resolutions.