Method for cyclic culture of photosynthetic microalgae

The invention provides a circulating photo-bioreactor. The circulating photo-bioreactor comprises a first culture portion, a second culture portion, and a pump portion connecting the first culture portion and the second culture portion, wherein, the culture portion comprises a culture pot which is filled with the medium and a first light source which is coupled to the culture pot, and the light source shines inside the culture pot; the second culture portion comprises a culture pipe which is arranged outside the culture pot and is filled with the culture from the culture pot and a second light source which is coupled to the culture pipe, and the light source shines inside the culture; and the pump portion is connected with the first culture portion and the second culture portion to let the culture solution cycle between the first culture portion and the second culture portion.