Abstract:There was a high frequency in the occurrence of abnormal plantlets during cotton (Gossypium hirsutum L. ) tissue culture. Their patterns, ways of development and effected factors, and the technique of their normalization were studied. Based on their morphologic characters, they could be classified into ten kinds, viz. growing point-abnormal plantlets, cotyledon-, hypocotyl-, united-, fasciculated-, single-leaf-, albino-, vitreous-, browning-, and callus forming plantlets. The growing point- and the cotyledon-abnormal plantlets, which were more commonly seen and were affected by multiple factors, are mainly influenced by the kind of explants, the medium composition, the method and time of culture. The abnormal plantlets could either developed from abnormal embryos or transformed from normal plantlets. Under suitable culture condition reversion of abnormality to normal was possible, however such normalization varied with different genotypes and media. The authors point out the interaction of external regulation and intrinsic developmental mechanism as the main factor causing the accurrence of abnormal plantlet and also discuss the technical procedures of reducing the occurrence frequency of such abnormal plantlets which greatly impact cotton tissue culture.