This paper demonstrates the use of particle swarm optimization technique for optimizing the parameters of blade pitch PI controller for wind power plant. A proportional –integral -differential (PID) controller is applied to a multivariable blade pitch controller for a wind turbine generating system comprising of a wind turbine driving a 3-phase synchronous generator connected to a large power system.The optimal PID parameters search is formulated as an optimization problem with a standard eigenvalue objective function. A time domain simulation of the system is then used in conjunction with the particle swarm optimizer to determine the controller gains. The eigenvalue-based performance index is considered. The results reported in this paper demonstrate the effectiveness of the particle swarm optimizer in the tuning of the PID parameters. The enhancement in the dynamic response of the power system is verified through simulation results. Results also revealed that the proposed controller obtained high quality solution and was able to provide a satisfactory compromise solution in almost all cases, thereby validating the efficacy of the proposed controller.