The invention relates to a brush roll cotton picker and belongs to the technical field of agricultural machinery. The brush roll cotton picker comprises a picking table, an air conveying device, a cotton boll separating device, an impurity cleaning device and a cotton collecting box which are arranged on a self-walking chassis, the impurity cleaning device comprises primary, secondary and tertiary tooth rollers, one side of the primary tooth roller is provided with an upper brush, one side of the secondary tooth roller is provided with a middle brush, one side of the tertiary tooth roller is provided with a lower brush, sides of the primary, secondary and tertiary tooth rollers are provided with interval arranged beating rods respectively, an upper brush roller is arranged below the primary tooth roller, a lower brush roller with bristles which simultaneously contact with outer circles of the secondary and tertiary tooth rollers is arranged below the secondary tooth roller, an arc barrier is mounted on the lower side of the tertiary tooth roller, one side in a casing, which is far from the beating rods, is provided with a cotton collecting flow channel which conveys air flow from bottom to top, and the cotton collecting flow channel is provided with upper and lower flow suction openings. The bottom of the cotton collecting flow channel is connected with an air outlet of a cotton conveying fan. By means of the brush roll cotton picker, cotton fiber damages can be remarkably reduced, the impurity cleaning effect is improved, the impurity content rate is lower than 10%, meanwhile, the recycling effect is enhanced, and the unginned cotton loss can be greatly reduced.