In this paper, simulation evaluation is done to know the working of LFC by building models in SIMULINK which helps us to comprehend the principle behind LFC which include the challenge. Main function of fuzzy logic based frequency controller is to improve the dynamic performance of frequency that means to keep the frequency balanced during sudden load change in power system. Variations in load bring about drift in frequency and voltage which in turn leads to generation loss owing to the tripping and also blackouts. These drifts might be reduced to the smallest possible value by Fuzzy logic control method. Load cannot be constant when load varies with time but gain values of conventional controller are constant. Thus to overcome the conventional controller, fuzzy logic based controller is considered for load frequency control problem. The simulation result shows that the proposed FLFC can provides good damping and reduces the overshoot even in presence of the generation rate constraint.