The aggregation of group loads, which consists of the linear and the non-linear systems, yields the error involved in the reactive power aggregation, which is greater than the active power aggregation in the component based load modeling. Each individual reactive power in a group load affects the aggregated load different from composition rate. This paper proposes a new method that determines the degree of impacts by adjusting the coefficient of weight factors of each load using the least squares error method. The effectiveness of proposed algorithm is demonstrated by simulating three aggregation cases.