The invention relates to the technical field of cotton planting, and discloses a cotton sowing device. The cotton sowing device comprises a rotating part and a fertilizer application part, wherein the rotating part comprises a first box body, a second box body, a rotating shaft and a motor; the motor drives the rotating shaft to rotate; the bottom of the first box body is provided with a first support post; the motor is fixedly arranged on the first support post; the upper part of the first box body is provided with a fertilizer tube; the first box body is provided with an opening; a separation plate is also arranged in the first box body; the separation plate and the side wall of the first box body form a seed cavity for placing cotton seeds; the rotating shaft is arranged in the first box body; the upper part of the rotating shaft is fixedly provided with a first helical blade; the fertilizer application part comprises a second box body rotationally arranged at the outer side of the first box body in a sleeving way; discharging wedge blocks are arranged at the two sides of the second box body; each discharging wedge block is provided with a through hole communicated with the opening; a second support post, a pressure spring and a slide block are arranged on each discharging wedge block. The cotton sowing device has the advantages that the fertilizer application and the sowing are completed in one step; the work efficiency is improved; the quantification is realized; through scientific planting, the cotton yield is improved.