Now-a-days the Flexible AC Transmission Systems (FACTS) is very popular and essential device in power systems. After introducing the FACTS technology, power flow along the transmission lines becomes more flexible and controllable. Several FACTS-devices have been introduced for various applications in power system. Before incorporating DG unit in the distribution system, it has to be ensured that the size and the location are critically decided. This underlines the importance of optimal DG allocation and sizing. This can be achieved by solving an optimization problem. In this work, a multi-objective optimization problem is formulated which aims at minimization of real power loss, improvement of voltage profile, enhancement of stability etc. subject to the operating constraints.