The invention discloses a cotton growing and fertilizing device capable of changing spraying amount. The device comprises a body, wherein the lower side of the body is rotationally connected with a first roller and a second roller; a power mechanism is arranged on the upper side wall of the body; the first roller is connected with the power mechanism through a transmission mechanism; a fertilizer box is arranged on the upper side wall of the body; armrests arranged in an inclined manner are fixedly arranged on the side walls of the body; a storage tank is arranged on the side wall of the fertilizer box; a cover plate is rotationally connected to an opening of the storage tank; a spray pipe is arranged in the storage tank and communicated with the fertilizer box through a hose; a pump is arranged at a communicating position of the hose and the fertilizer box; and a nozzle is connected to one end, which is far away from the hose, of the spray pipe. The device disclosed by the invention is simple in structure and convenient to operate, and the amount of the sprayed fertilizer can be changed in a manner of changing the spraying amount aiming at geological differences in different regions, so that convenience is brought to use of workers, and the fertilization efficiency is improved.