Abstract: The current study explored physiological characteristics of Chlorella cultivated under axenic culture in the designed simulator with a set of optimized parameters, including light intensity, temperature and nutrient concentrations, by mainly measuring intracellular contents of C, N, P and photosynthesis fluorescent parameters. The experiment employed the Batch culture+ Continuous culture cultivated mode to simulate the formation of algal bloom, and the cultivation period was divided into five phases according to the growth curve. Results showed that Chlorella had highly photosynthetic activity, and the growth was not inhibited by light intensity, temperature and nutrient concentration during adjustment phase. While in exponential phase, the growth of Chlorella was inhibited by light intensity, and heat dissipation was enhanced and intracellular contents of C, N and C/N ratio were high. At stable period, Chlorella was simultaneously inhibited by light intensity and nutrient concentration, and intracellular contents of N, P and N/P ration decreased. In continuous culture phase, when nutrient limitation was mitigated, both photosynthetic activity and the nutrient absorption ability of Chlorella were enhanced. This implied that monitoring the turning point of intracellular nutrients and changes in intracellular element ratio provided a reference basis on the study of the formation, persistence and fade of algal bloom.