Nano cellulose from plant fibres were selected as reinforcement. Sansevieria Trifasciata and Pandanus Utilis were selected as the source of the biomass. Polyester resin was selected as the matrix. The investigation involved the variables type of CNC and Wt. % of CNC in the matrix. Full factorial design of experiment was carried out. Composites was manufactured under vacuum and tensile and flexural test were performed as per ASTM standards. The maximum tensile and flexural strength were noted at 5 Wt.% of CNC, the mechanical strength of S.T CNC reinforced composite was always higher than that of P.U CNC one. A general increase in strength was noted as wt. % of CNC increased for both biomass.