This search aims to study the effects of (SSSC)”static synchronous series compensator– one of the FACTS devices” – on reducing the power losses and improving voltage profile of Iraqi national grid system. Proposed particle swarm optimization (“PSO”) to determine the optimum location of “SSSC” devices based objective function that depends on the power and voltage as fitness. The proposed algorithm is checked on the IEEE- 9bus. Then is applied on the Iraqi national grid. The results show the ability of the proposed method to determine the optimum location of static synchronous series compensator (SSSc) that reduced losses of active power and improve the bus “voltage profile”. The proposed algorithms are implemented by using MATLAB package version 7.10