In this work, the vibrational behavior of luffa cylindrica/USP composites has been addressed. The effect of fiber dosage with difference fiber content from 30, 40, 50% and chemical treatment (NaOH) are analyzed. The specimens are fabricated with compression molding technique with pressure of 17 MPa. For the production of composite specimens, untreated and NaOH treated fiber were used as reinforcement and unsaturated polyester resin (USP) used as matrix. The prepared specimens are cut as per the ASTM standard, and mechanical and vibrational tests were conducted. The experiential nodal analysis is used to fine the natural frequency and damping of the composites. The results depicts that the increase in fiber dosage started to improve the mechanical properties of the composite beam. The NaOH treatment showed the improvement in mechanical and damping of the composites. The 50% fiber dosage showed the good tensile and flexural properties of the composites. The interfacial mechanism of the composites was interpreted in the SEM.