Abstract: Based on energy consumption theory of visco-elastic material under dynamic pressure and elastic plate theory and generalized Kalvin solid model for covering layer,sag resistance energy consumption mechanism of belt conveyor is analyzed in this paper.Formulas of sag resistance and resistance coefficient are deduced.Combined with technical parameters of conveyor and Matlab software used,every influence factor is analyzed and result show that the theoretical formula can reflect rightly influence of every factor on sag resistance.