Power system stabilizers (PSSs) are added to excitation system to enhance the damping during low frequency oscillations. This paper presents a study of fuzzy logic power system stabilizer (PSS) for stability enhancement of a multi-machine power system. In order to accomplish the stability enhancement, speed deviation (Deltaomega) and acceleration (Delta macromega) of the rotor of synchronous generator of multi machine power system were taken as the input to the fuzzy logic controller. These variables take significant effects on damping on damping of the generator shaft mechanical oscillations. The stabilizing signals were computed using the fuzzy membership functions depending on these variables. The simulations were tested under different de-fuzzyfication methods. The simulation results are quite encouraging and satisfactory.