Abstract: An apparatus for carbon dioxide-capture system has a cultivating vessel and at least one basking mechanism. The cultivating vessel has a reservoir for accommodating alga culture. The basking mechanism is mounted in the reservoir of the cultivating vessel and has multiple trays and a circulating mechanism. The trays are imbricately mounted on the basking mechanism with predetermined intervals and each has at least one spout formed at an overlap with an adjacent tray. The circulating mechanism is mounted between the trays and the reservoir. The alga culture is pumped into one tray by the circulating mechanism, flows through the spout into another tray, enhancing a rate of carbon fixation by alga.