This experiment addresses the influence of fiber, nanocontent, surface treatment and compression pressure in natural frequency and damping factor of sisal/coir/alumina nanocomposites. Taguchi method and gray relational analysis were carried out for finding the optimized process parameter for this impact hammer test. Biosynthesized nanoalumina from neem leaf was applied as the filler. Grey relational grade concluded that sisal, coir wt with 20%, 15%, alumina nano % 2, NaOH treatment with 5% and compression pressure with 10 MPa as the optimized working condition for this whole vibration procedure. Lesser diameter of sisal (100-200 mu m) than coir fiber makes sisal the vital role in the damping nature of hybrid composites than other factors. Lesser diameter makes wider interface making enhancement in the property. SEM testing was adopted after tensile, flexural and impact tests for determining fractured surface of natural composites.