The utility model relates to a cotton and shell separator which is mainly composed of a cotton and shell separating and transmitting mechanism, a secondary cotton cleaning mechanism and a pure seed cotton delivery mechanism, wherein the cotton and shell separating and transmitting mechanism is composed of a shelly cotton feeding device 1, a cotton and shell separator 2, a three-stage tooth roller 3 for discharging cotton shells and impurities, all of which are connected by a motor in a transmission way. The three-stage tooth roller is formed by the series connection of three tooth rollers with unequal diameters. One side of each tooth roller is provided with shell discharge screen nets 4. The secondary cotton cleaning mechanism is formed by the connection of a plurality of arc-shaped plates 5 arranged on one side of each tooth roller, and a clean cotton return slide plate 6. The pure seed cotton delivery mechanism is composed of a gear guide mechanism 7 and a discharging and sending channel 8. The cotton and shell separator is used for separating cotton from shells after the shelly cotton is picked off and is sent into the cotton and shell separator, and thus, the utility model can be used both indoors and outdoors. The separating speed of the utility model is hundredfold of people's cotton stripping speed, and the efficiency of discharging shells and removing impurities reaches over 98 permillage.