The invention discloses a micro alga cultivation system. The system comprises a transparent container containing water and micro alga； an LED lamp, which is placed in a sealed element and then placed in the transparent container for illuminating the micro algae； and a PWM controller, which is coupled to the LED lamp to control brightness/darkness contrast ratio of the LED lamp. The system may increase the growth rate of the micro algae. It can maintain the micro algae concentration and save 10% to 15% electricity consumption.本案係揭露一種微藻類養殖系統，其包括：一透光容器，其中置有水及微藻類；一LED燈管，係套置於一密封件中後置於該透光容器中，可發出光源照射該微藻類；以及一PWM控制器，耦接至該LED燈管，可控制該LED燈管的閃爍亮暗比。藉由上述之養殖系統可使藻體生長速度明顯提高，不但可維持藻體濃度，更能節省10.0%-15.0%之電力消耗
