In this study, a saline-alkaline tolerant microalgal strain was isolated and identified as Chlorella sp. LPF. This strain was able to grow at pH values up to 10 and at salinities up to 5%, and tolerated to 80gL(-1) of sodium bicarbonate. The utilization of bicarbonate as carbon source significantly promoted microalgal growth and lipid production. In the non-sterile cultivation supplying with 80 g L-1 of sodium bicarbonate, the microalgal growth had no difference with their growth in the sterile medium; however, the bacterial growth was suppressed and the cell number decreased to low levels after six days cultivation. This study gives an insight into the potential that using high concentration of sodium bicarbonate as external carbon source to cultivate microalga in non-sterile condition, and suggests a possibility of using bicarbonate as growth promoter and antibacterial agent for the microalgal outdoor cultivation.