Nitrogen-limited culture is a kind of method improving the oil content of Chlorella sorokiniana.The biomass,water content and fluorescence parameters of chlorella cultivated under nitrogen-limited medium were investigated.The results showed that the biomass and water content of chlorella under nitrogen-limited culture declined 18% and 7%,respectively;the maximal photochemical efficiency of PSⅡ (F_v/F_m),apparent quantum efficiency (α) and maximum photosynthetic electron transport rate (rETR_max) rapidly fell during the course of nitrogen-limited culture,and fell to close zero by the later period of culture;the minimum saturating irradiance (E_k,light-resistant index) firstly rapidly decreased from the early logarithmic period,and then remarkably increased during stable period;the minimum fluorescence(F₀) obviously increased during the nitrogen-limited culture.These results showed that nitrogen-limited culture significantly influenced the structure and function of PSⅡ in chlorella.