By integrating the reactive power of the distributed generators (DGs) to be the control variables, the reactive power optimization problem in distribution power system with DGs is discussed。This paper analyses the change of the network loss when DG access to distribution network, and established the minimum active network loss as the objective function of optimization model.A bacterial colony optimization(BCO) algorithm based on the basic growth law of bacterial colony is presented.A bacterial colony optimization algorithm based on the basic growth law of bacterial colony is presented.Finally,the effectiveness of the proposed algorithm are illustrated by experiment of IEEE-33 nodes system.