This paper presents Gravitational search algorithm (GSA) optimization techniques for the optimal location of Flexible AC Transmission System (FACTS) devices in the power system network to attain minimum transmission active power loss, the optimal value of control variables, and optimal bus voltage. These proposed methods are legitimate in the IEEE-30 test bus system. Here, the proposed GSA algorithm is adapted for minimization of active power losses and it is also improving bus voltage. After using facts devices, from the obtained results power system loadability improved within range and at different loading condition in the power system networks all generators capable to dispatch a significant amount of active power. By incorporating facts devices, we proposed active power loss reduced and also maintained the bus voltage of the power system network at different loading condition. Hence, for Loadability enhancement in the power system, this gives a better optimal solution.