This article presents contingency analysis of power system by Fast Decoupled Load Flow method using Mi-power software. In the modern days the power system is becoming wide and complex and hence system security is one of the challenging tasks for the operation engineers. Contingency Analysis (CA) is critical in power system analysis and it gives the knowledge about the system state in the event of a contingency. Contingency analysis technique is being widely used to predict the effect of outages like failures of equipment, transmission line etc, and to take necessary actions to keep the power system secure and reliable. The off line analysis to predict the effect of individual contingency is a tedious task as a power system contains large number of components. Practically, only selected contingencies will lead to severe conditions in power system. The process of identifying these severe contingencies is referred as contingency selection. In this work single line outage contingency case is analyzed for different loading conditions and demonstrated through IEEE 6-Bus System.