Abstract: In order to promote the coordinated development of runoff small hydropower and the regional distribution network, a method for calculating the optimal hosting capacity of runoff small hydropower is presented by considering adaptive reactive power control in this paper. For improving the economy and power quality of the distribution network, by taking the integrated optimization of running costs, voltage offset and power loss as the objective, a multi\|objective model based on chance constrained programming is built by applying multi\|state model. An adaptive control strategy of reactive power is used to solve the voltage regulation problem of grid\|connected nodes. Moreover, non\|dominated sorting genetic algorithm II (NSGA\|II) based on elitist strategy is proposed to solve multi\|objective model, and technique for order preference by similarity to an ideal solution (TOPSIS) based on information entropy is adopted to choose the optimal solution from Pareto solution set. In the end, the simulation results on IEEE\|33 distribution system demonstrate the effectiveness of the proposed approach.