This paper represents vibration analysis of Sisal fiber reinforced epoxy based composites using Fast Fourier Transform (FFT) analyzer. The composites were prepared by melt-mixing method, followed by compression molding process. The percentage of sisal fiber is varied from 4% to 10% in steps of 2%. Thermo gravimetric analysis (TGA) is done to understand moisture absorption and moisture content. We also report vibrational analysis to understand the influence of fiber loading on natural frequency and damping coefficient.