A new type of negative pressure photobioreactor was used to explore culture effect of feeding microalgae-Thalassiosira weissflogii. The change of algae density, the quantity of heterotrophic bacteria and Vibrios, the mass concentration of ammonia nitrogen and nitrite nitrogen, and their relationship were investigated. Thalassiosira weissflogii grew fast and reached plateau stage on the 4th day of culture, the highest value of algal density was 1.5×10⁶ cells/mL,and the specific growth rate was 1.37. Quantities of vibrios and heterotrophic bacteria ranged from (0.19-2.70)×10⁴ cfu/mL and (0.071-0.93)×10⁶ cfu/mL, respectively. Compared to the plateau and decay periods, algae had strong inhibition on bacteria in the exponential growth stage, especially vibrios. The mass concentration of ammonia nitrogen and nitrite nitrogen in algae solution were accompanied by increased algae density, and the highest value was 0.24 mg/L and 0.37 mg/L, respectively. The algae density was positively correlated with the mass concentration of ammonia nitrogen and nitrite during the exponential growth period (P<0.05). The negative pressure photobioreactor could shorten the cultivation period, inhibit the growth of bacteria,improve the cultivation efficiency and the quality of algae solution. It is a system suitable for feeding microalgae culture. But it's worth noting that the algae solution should be fully aerated to reduce the mass concentration of ammonia nitrogen and nitrite nitrogen before feeding the larvae. This study provides reference for the application of negative pressure light bioreactor as feeding microalgae culture system.