Scenedesmus sp. 200716 and Chlorella sp. XQ-20044 with different nitrogen concentrations were carried out in a circular pond mimic system to characterize its growth and lipid production. Both of the strains grew quickly while the total lipid content was relatively constant (about 20% of dry biomass) before stationary phase. However, lipid accumulation began as cell division ceased in the stationary phase. After 12 days of cultivation with 1mM and 3mM sodium nitrate, total lipid content reached 55.0% and 54.3% dry weight of Chlorella sp. XQ-20044, 32.1% and 29.7% dry weight of Scenedesmus sp. 200716, respectively. The data clearly demonstrated the unparalleloccurrence of cell growth and lipid accumulation, which was stated here as two-stage characteristics of lipid production: The first, cell production stage, algal cells divide quickly to produce large amount of biomass, then followed by lipid production stage, cell division cease andlipid accumulation begin. Based on these results, the strategies for efficient lipid production by mass culture of green algae were further discussed.