Polyploidization is an important way of speciation and plant breeding. In this study,the autopolyploid of Gossypium herbaceum progenies S1 in the early stage were used as materials,and flow cytometry,morphological,cytological and SRAP molecular marker were used to identify them. The results of flow cytometry for ploidy identification indicated that the fluorescence peak value of diploids was used as a reference,among eight polyploid progenies,there were 5 triploid plants and 3 tetraploid plants,respectively. The results of morphological identification showed that compared with polyploids,diploid plants were taller with thinner stalks,as well as thinner,smaller and emerald green leaves,and flowers were smaller. Compared with diploids,triploids and tetraploids all presented shorter and thicker stalks,as well as thicker,shrunken,larger and dark green leaves,and flowers were larger. The results of cytological identification demonstrated that with the increase of ploidy level,it showed a downward trend for stomatal density,while it all showed an upward trend for the length of stomatal,the number of chloroplasts and the diameter of pollen grains. There were normal and abnormal behaviors during meiosis in pollen mother cell for all diploids,triploids and tetraploids,including monad（0.17%,2.50% and 2.17%）,dyad（0.33%,0.67% and 0）,triad（4.17%,10.00% and 2.33%）,normal tetrad（94.83%,54.00% and 73.67%）,abnormal tetrad（0.17%,0.33% and 0.83%）and polyad（0.33%,32.50% and 21.00%）respectively. The abnormal polyad could not produce normal pollen grains,thus the proportion of normal pollen grains in the diploids,triploids and tetraploids were 95.33%,58.83% and 77.67% respectively. The results of SRAP molecular marker identification revealed that there were three polymorphism bands amplified in triploids and tetraploids：including completely consistent with diploids bands,lost bands and new specific bands when comparing with diploids. The genetic proportion of three band types in the triploids were 80.81%,6.73% and 12.46%,and that of the tetraploids were 76.59%,10.37% and 13.04%,respectively. This confirmed the authenticity of polyploidy at the molecular level.
