Multi-machine power system stability improvement by tuning of Static Var Compensator (SVC)-based controller parameters is investigated in the proposed method. The design problem is formulated as an optimization problem with a timedomain simulation-based objective function and Real-Coded Genetic Algorithm (RCGA) is used for searching optimal controller parameters. A multi-machine power system model is developed using MATLAB's SIMULINK which incorporates SVC Controller. A fault is created on the transmission line. The simulation results of the multi-machine power system without SVC Controller and with SVC Controller are presented. The simulation results are analyzed which shows that the power system becomes unstable on the occurrence of the fault if SVC controller is not used. This paper shows the effectiveness of the proposed design. The proposed method enhances the multi-machine power system stability.