Short-circuit current is strongly related to the cost of apparatus and the efficient use of power transmissions. Therefore, the introduction of Superconducting Fault Current Limiters (SFCL's) becomes an effective way for suppressing such a high short-circuit current in loop power systems. Firstly, a method to obtain a smaller SFCL capacity by observing the SFCL behavior including sub-transient and transient effects during a short circuit is proposed. Secondly, we propose using a micro-genetic algorithm (micro-GA) combined with a hierarchical genetic algorithm (HGA) to simultaneously search for the optimal location and the smallest SFCL capacity. The efficiency of the proposed method is shown by numerical examples with a loop power system.