This paper proposed a Power System Stabilizer model based on Fuzzy-PSO for improving power system stability. Power System Stabilizer (PSS) is equipment that can be used to enhance the damping of power system during low frequency oscillations. For large scale power systems comprising of many interconnected machines, the PSS parameter tuning is a complex exercise due to the presence of several poorly damped modes of oscillation. The problem is further being complicated by continuous varied in power system operating conditions. In order to enhance the performance of PSS, the combination of fuzzy logic and particle swarm optimization (PSO) method is used in this study. Simulations were carried out using several fault tests at transmission line on a two-area multi-machine power system. As a reference the PSS model, Delta w PSS and Delta Pa PSS has been used for comparison with the PSS under considerations. The result shows that power transfer response using the PSS model is more robust than Delta w PSS and Delta Pa PSS, especially for three phase faults and phase to ground faults.