We studied the mercury stress of through potted 1-year old seedlings four different energy willow clones (N2,N4,NC,NE),and conducted Hg²⁺ stress experiment,measured the physiological and biochemical indices,then all the parameters were used to evaluate the potential Hg²⁺ tolerance through the subordinate function method and screening out the tolerance heavy metal Hg²⁺ potential energy willow clones.The results show that:(1)With the rise of the soil Hg²⁺ concentration,the four energy willow clones protective enzymes POD,SOD and CAT activities showed a trend of increased and then decreased,the resistance of the 4 energy willow clones is different,but NC’s POD and CAT activities still higher than CK under severe stress;(2)The content of soluble protein and proline in the leaves of all clones are showing a trend of increased and then decreased with the heavy metals Hg²⁺ stress intensifies,all the energy willow clones reached the peak in the mild or moderate stress,and the rate of decline of soluble protein content is larger,this phenomenon showed more obvious in NC and NE clones;(3)With the heavy metals Hg²⁺ stress intensifies,the root activities of N2,N4 and NE showed a trend of decreased,but NC’s rise slightly under mild stress,then showed a trend of decreased;and the content of MDA of four energy willow clones showed a trend of decreased,and reached the significant level under moderate and severe stress;(4)Under mild Hg²⁺ stress,N4 and NE’s chlorophyll content and Chl a/Chl b value are presented descending trend,while N2 and NC’s is slight rise ;under moderate and severe stress,four energy willow clones chlorophyll content and Chl a/Chl b value are fallen rapidly,but the rate of decline of four energy clones are differences,the rate of decline of N4 is maximum,NC’s is minimum;(5)Using membership function of fuzzy evaluation method for comprehensive evaluation of four energy willow clones of Hg²⁺ tolerated,the result indicated that:Salix C>Salix E>Salix 4>Salix 2.Thereby under different intension of Hg²⁺ stress,four energy willow clones can adjust its protective enzymes activities,GSH content and organic osmolytes content to relieve the stress of Hg²⁺,showing some tolerance to heavy metal stress of Hg²⁺,and the tolerance potential of NC is the best.