The utility model relates to the field of microalgae culture photobioreactor. The flexible plate photobioreactor disclosed by the utility model comprises flow channels and further comprises a reactor culture solution inlet (1), a reactor culture solution outlet (2), a main film (5), rib plates (6) and a drawstring (7), wherein the flow channels are separated by virtue of the rib plates (6); the reactor culture solution inlet (1) and a flow channel culture solution inlet (8) form a reactor culture solution inlet cavity (10) and the reactor culture solution outlet (2) and a flow channel culture solution outlet (9) form a reactor culture solution outlet cavity (11); the drawstring (7) is arranged inside the reactor culture solution inlet cavity (10) and/or the reactor culture solution outlet cavity (11). According to the photobioreactor disclosed by the utility model, the overall structure of the photobioreactor is optimized; the service life of the flexible plate photobioreactor is prolonged; the risk of the fracture caused by aging, stress and the like of the photobioreactor is reduced.