Dwarf cotton has the advantage in lodging resistance and suitable for dense planting， which is conducive to shaping ideotype of cotton plant architecture， optimizing population performance， improving photosynthetic productivity and increasing yield per unit area. A plant architecture mutant was found in the distant hybrid line N31. Following continuous self-crossing for multiple generations， a stable homozygous mutant was obtained and named as df31. Phenotypic investigation showed that df31 decreased in plant height， branch angle， internode length， while elongated the growth period than N31. Genetic analysis showed that the segregation of mutant phenotype and normal phenotype present in a ratio of 1∶3 in an F₂ population， which indicated that the short stature mutation was controlled by a single recessive gene. The cytological observation showed that compared with N31， the number of parenchyma cells in a unit area in petiole， hypocotyl and stem of df31 increased， accompanying with more vascular bundles and less developed cambium. Along the vegetative growth， the content of endogenous GA₃ and BR in df31 showed an obvious decreasing， the content of IAA was not affected， and its growth rate was slow. Through this study， the comprehensive phenotypic identification of the dwarf mutant df31 and the genetic basis of dwarf gene underneath were analyzed， furthermore the dwarf mutations were analyzed at the cellular and physiological levels， which laid the foundation for further studies on gene mapping and cloning.