The element composition of 20 kinds of hard aluminum wires for overhead transmission lines was analyzed

and the relationship between the content of each impurity element and the conductivity was investigated.The results reveal that the total amount of impurity elements is not completely negative linear to conductivity

while the trace impurity elements Ti

V

Mn and Cr have significant effects on the conductivity.Proper amount of boron can effectively improve the conductivity

while rare earth elements can be ignored for effect on wires.Under the condition that the total amount of impurity elements is less than 0.20%

only when w（Ti+V+Mn+Cr）is less than 0.001%

w（Fe）is less than 0.10%

and w（Si）is less than 0.05%

the conductivity of hard aluminum wire can be higher than 36.25 MS/m

and that of the related annealed aluminum wire can be guaranteed to reach above 37.12 MS/m.