Aiming at the existing distribution capacity in charge of low, fixed costs cannot be completely recycled, and not considering the problem of load rate, the rate of electricity is applied to the distribution of electricity, through the transmission and distribution cost analysis. The rationality of the allocation capacity cost using BARY curve is discussed, fully considering the load characteristics of the user, the user to step through clustering method, the piecewise regression straight line method for determine the capacity of the cost in the basic price and electricity price of share proportion of technical means, BARY curve is presented. The model of capacity cost allocation based on piecewise regression line method is proved to be reasonable, fair among users with different load rates and feasible in pricing through empirical analysis.