Selected nine cotton cultivars of different genotypes as experimental materials,the effect of regulating of source-sink ratio on some premature senescence characters were studied by removing basal two fruiting branches.The results showed that:(1)Regulating of source-sink ratio at early reproductive growth stage had great influence on transmitted photo-synthetically active radiation (TPAR),LAI,variation rate of SPAD in the leaf subtending seasonal boll,fruit abscission rate,red stem rate and single boll weight.The differences between control and treatment were significant (P＜0.05) or very significant (P＜0.01).The strength of delaying senescence was increasing with the growing process by removal of early fruiting branches.(2)The effect of delaying senescence was difference among different cotton genotypes by regulating of source-sink ratio at early reproductive growth stage.Clustering analysis indicated that the effects of retarding senescence on three cotton cultivars (Jiza-999,GK-34,QY-2) were the best,effects on five cotton cultivars (LuHBbiaoza-1 for example) were weak and effect on Chuanzamian-3 was intervenient.The above results suggested that cotton premature senescence could be delayed by removing basal fruiting branches at early reproductive growth stage,while the performance of retarding effect was inconsistent among different cotton genotype.