The invention discloses a seaweed culture tank which comprises a main tank body and a driving motor. The driving motor is fixedly connected with one end of the outer wall of the main tank body, a baffle is arranged on the top of the main tank body in an inserting mode, a socket corresponding to one end of the baffle is formed in the inner wall of the main tank body, one end of the baffle penetrates through the socket, a clamping block is fixedly connected to the end of the baffle, a locking opening is formed in the end, far away from the baffle, of the clamping block, a locking screw is in threaded connection with the interior of the locking opening, a threaded groove corresponding to the locking screw is formed in the outer wall of the main tank body, a worm is fixedly connected to the output end of the driving motor in a sleeving mode, the end, far away from the driving motor, of the worm penetrates through the outer wall of the main tank body and extends inwards, and the extension end of the worm is rotationally connected with the inner wall of the main tank body. Accordingly, by additionally arranging a transmission mechanism, seaweed in the culture tank is made to keep a motion state, so that the growth rate of the seaweed is guaranteed, and the culture earnings of farmers are increased.