Abstract: The paper aims to determine the suitable planting density of 3 main varieties in south-central Hebei. The authors set up 3 planting densities (45000 plants/hm2, 75000 plants/hm2 and 105000 plants/hm2) to study their effects on growth, yield and quality of the 3 cotton varieties. The results showed that: with the increase of planting density, the thick stems, branch numbers, boll numbers per plant, boll shedding numbers and rotten boll numbers decreased; the numbers of boll per unit area increased with the planting density; the seed cotton yield of‘Jimian 958’was the maximum under the density of 75000 plants/hm2, and the yield of ‘Shikang 126’and‘Ji 863’under the planting densities of 75000 plants/hm2 and 105000 plants/hm2 were greater than the yield under the density of 45000 plants/hm2, and the differences of seed cotton yield under the 2 relatively high densities were not significant. Therefore, the suitable planting density of‘Jimian 958’is 75000 plants /hm2, and that of‘Shikang 126’and‘Ji 863’is from 75000 plants/hm2 to 105000 plants/hm2.