Problem statement: The inter-area power systems have special characteristic of the stability behavior. The improvement of inter-area power system is one of the important aspects in power system. Approach: This study applies the Static Synchronous Series Compensator (SSSC) to improve stability of inter-area systems. The SSSC is modeled and then is applied to be incorporated into the power system model for investigating stability improvement. The SSSC is modeled as the variable susceptance and is controlled during dynamic state. This presented SSSC model can be incorporated into susceptance matrix of power system model. The presented method is tested on sample inter-area power system with 3 phase fault distubrances. Results: The swing curve of inter-area power system without a SSSC gets increases monotonically and thus the system can be considered as unstable whereas the swing curves of system with a SSSC can be considered as stable. Conclusion: From the simulation results, the SSSC can enhance stability of inter-area power systems.