Earth resistance reduction methods for the transmission line towers in Yunnan Power Grid are summarized and evaluated.By grading the tower earth resistance

an index of "unit degrading input cost" is introduced to synthetically consider the input cost and the profit

thus a new evaluation approach of tower earth resistance reduction methods is proposed.In addition

the "cost（C）/utility（B）" evaluation method is employed for economic analysis and quantitative evaluation of tower earth resistance reduction.Four commonly used tower earth resistance reduction methods are analyzed

and their advantages and disadvantages are evaluated with the proposed approach.The results show that

in comprehensive consideration of the earth resistance

the economic analysis of expansion and the corrosion condition

appropriate tower earth resistance reduction method should be selected according to the over-standard extent of the earth resistance.Moreover

some suggestions are offered for improvement of the conventional earth resistance reduction methods.