Abstract: The objective of the study was to discuss effects of gradual cooling treatment on chilling injury and endogenous polyamine contents,and clarify gradual cooling treatment to improve the chilling-resistance mechanism of ‘86-1' Hami melon(Cucumis melo L.)fruits after postharvest.The effects of direct cooling(1 ±0.5) ℃ and gradual cooling treatment(8±0.5) ℃,1 d→(5±0.5) ℃,3 d→(3±0.5) ℃,3 d→(1±0.5) ℃ on chilling injury index,chilling injury incidence,membrane permeability and endogenous putrescine,spermine,spermidine,total polyamine contents of ‘86-1' Hami melon(Cucumis melo L.) fruits were investigated and analysed. The results showed that:the gradual cooling treatments could significantly reduce chilling injury index and chilling injury incidence, inhibite in membrane permeability, improve endogenous Put, Spm and Spd content. The correlation analyses showed an positive correlation( r =0.873, p <0.05) between endogenous Put content of‘86-1' Hami melon and chilling injury index. And significantly negative correlation between endogenous Spm and Spd content of fruits and chilling injury index(r=-0.939 and r=-0.986,p<0.01).