In our experiment,28 hulless barley cultivars were choose to study their water consumption rate and dehydration rate when the first leaf spread out.A droughttolerant and a watersensitive hulless barley cultivar were selected.To understand the regulating effect of polyethylene glycol (PEG) under drought stress ,we examined the effects of 5%~30% PEG pretreatment on the seed germination,seedling growth and physiological characteristics of different barley varieties.The results were as following:(1)Relative water content of 28 hulless barley varieties increased gradually,while dehydration rate showed the opposite trend.The relative water content ranked the highest (60.16%) and dehydration rate ranked the lowest (8.80%) in Handizi,while relative water content ranked the lowest (38.98%) and dehydration rate ranked the highest (20.20%) in Dama,it indicated Dama was greatest sensitive to water and Handizi was least sensitive to water.(2)Germination and rooting rate in hulless barley seed,root length,shoot height and fresh weight in hulless barley seedlings showed ‘rises first,falls later’ with the increase of PEG concentration.The best treatment concentration on Handizi hulless barley and Dama were 15% and 10% respectively and the difference was significant with the control (P<0.05).The best treatment concentration on root length,shoot height and fresh weight in two hulless barley seedlings was 10% and no significant difference was found between the treatments and the control in Dama.(3)Soluble protein and chlorophyll content of Handizi hulless barley leaves was correlation with PEG concentration and malondialdehyde (MDA) presented negatively correlation.They were obvious at 0.01 degree in 30% PEG.Soluble protein and chlorophyll content of Dama hulless barley leaves showed ‘rises first,falls later’,and the MDA showed the opposite change.20%PEG was the best treatment.To sum up,low concentration of PEG pretreatment promoted seed germination,seedling growth and improvement of physiological function of hulless barley;high concentration of PEG inhibited seed germination,seedling growth and improvement of physiological function of hulless barley.The variety with stronger drought tolerance had a strong resistance to PEG and self regulation ability from the beginning of seed germination period,and the variety with weak drought tolerance had a weak resistance and self regulation ability when subjected to higher degree of stress.So the treatment of appropriate PEG concentration not only could significantly promote the seed germination and seedling growth of hulless barley,but also could improve the physiological function,including protein,chlorophyll,MDA content and relative conductivity,which could enhance the resistance ability.The results of this study suggested that it can make dormant seed rapidiy activing using a proper concentration of PEG solution to soak,and improve the efficiency of seed breeding,which lays a foundation for the PEG widely application in agriculture.