Biogeography is defined as the investigation of dispersion of biological species in ecosystem and it can analogous to the mathematical optimization problems in the field of engineering, medical science, economic science, sport, business enterprise, town future planning and so on. The proposed Improved Biogeography Based Optimization (IBBO) algorithm is roused on fundamental basis of scientific mechanisms of actual biogeography. This paper purports the IBBO technique to identify the optimal power rating and position of distribution generation (DG) in radial distribution networks. Since the distribution line loss minimization plays a vital role in economic operation of power system, hence the distribution line active power loss is elite as the target fitness (objective) function for the proposed optimization problem. The simulation studies are implemented in MATLAB software for IEEE 33-bus and IEEE 69-bus radial distribution test networks. Results incurred from the purposed approach prove that better active power loss reduction and improved node voltage profiles when compared with other existing methods available in the literature. © 2017 IEEE.