The works expresses that the experiment work on the free vibration on the luffa cylidrica/ polyester composites. The influence of fiber loading and chemical treatment are analyzed. The composites beam structure are fabricated using the compression molding technique with optimum pressure of 17MPa. The NaOH treated and untreated fiber were utilized for production of composites. Specimen were prepared according to ASTM standard. By using the experiment nodal analysis, the natural frequencies and damping vales were found. The results shows that the increases in fiber loading initiated to enhance the mechanical properties of the composites but decrease the damping value. The chemical treatment also improves mechanical and damping behaviors of the composites. The 50% fiber loading produces the better tensile and flexural properties. Scanning electron microscope reveals the interfacial mechanism of the composites.