An algae growth method comprises the steps of: mainly providing a cultivation liquid to cultivate algae having an initial concentration provided with an optical density (OD) value of 0.04~0.06, in which a cultivation temperature is controlled at the range of 25~30 DEG C； performing irradiation by a light-emitting diode (LED) having irradiation intensity of 3000~8000 lux for 12 to 24 hours； continuously supplying carbon dioxide (CO2) during a cultivation process at an aeration intensity of at least 2000 c.c./min； and performing ultrasonic irradiation in the cultivation process, in which the ultrasonic irradiation has a frequency ranged between 0.5~3.5 MHz and a voltage of 5.5 Volt, performed in an irradiation period of ten seconds to five minutes per eight hours. Accordingly, with the ultrasonic irradiation technique, the algae production can be increased and optimized, and the algae can be cultivated in a limited indoor space with an enhanced productivity.一種綠藻增長方法，主要是取初始濃度之OD值為0.04~0.06之綠藻培養於一培養液中，其培養溫度控制在25~30℃，以照射強度3000~8000 lux之LED照射12~24小時，且在培養過程中以打氣強度至少2000 c.c./min持續供給CO2，並於培養過程中施以超音波照射；其中，超音波照射之頻率為0.5~3.5 MHz，電壓為5.5 Volt，並於每8小時照射10秒~5分鐘。利用超音波照射技術增加藻類產量，以達到綠藻產量最佳化，使其能夠在室內有限空間內便能栽培養殖並增加產能。
