Fast progression in field of power electronics has already started influence of the power industry. So Flexible AC Transmission System (FACTS) devices provide fast control of active and reactive power through a transmission line. In this paper, transient stability will improve by using UPFC. The unified power flow controller is a member of FACTS family with very attractive features. This is the combination of the properties of STATIC synchronous compensator (STAT com) and Static Synchronous Series Compensator (SSSC).