This paper presents a method for determining radial configuration of distribution network which is used in reconfiguration problem and an effective method based on Gravitational Search Algorithm(GSA) to identify the tie switchs in distribution network with Distributed Genf!ration (DG). The main objective is to reduce the real power losses in the system while satisfying all the distribution constraints. To demonstrate the validity of the proposed algorithm, computer simulations are carried out on 8 buses, 16 buses, 33 buses, 69 buses systems and the results are presented and compare with the TOPO/PSS-Adept software and PSO Algorithm. The simulation results have showed that the method of determining the radial configuration enables the optimization algorithms do not lose results and GSA algorithms are powerful optimization algorithm with a fast convergence and can be applied in reconfiguration distribution network problems having large searching space.