This paper presents a multi-objective Pareto optimal method for allocation of fault current limiters(FCLs)based on an immune algorithm(IA),which takes into account two objectives of the cost and fault current mitigation effect.A sensitivity factor calculation method based on the rate of fault current mitigation is proposed to reduce the search space and improve the efficiency of the algorithm.In this approach,the objective functions related to the cost and fault current mitigation effect are established.A modified inversion operator based on equal cost is proposed to converge to global optimal solutions more effectively.The proposed algorithm is tested on the IEEE 39-bus system,and obtains the Pareto optimal solutions,from which the user can select the most suitable solutions according to the preferences and relative importance of the objective functions.Simulation resul ts 50 are used to verify the proposed method.