This research aims to study the application of coconut meal corn cob and durian peel as wood-substituted biocomposites in medium density fiberboard. The fiber: urea formaldehyde glue: isocyanate glue with polymeric diphenymethane diisocyanate type (pMDI) ratio is equal to 1: 0.13: 0.003. The fibers are taken from coconut meal corn cob and durian peel that 7 ratios are used to all of fiber mixing. The fiberboard production use 130°C of temperature with 20 – 50 kg/sq.cm of compressive pressure with 8 minutes per piece of rate. Their fiberboards have 603 – 856 kg/m of density that was tested follow the TIS 876-2547 standard. Resulting the MM33 ratio (coconut meal fibers: corn cob fibers: durian peel fibers is equal to 0.33: 0.33: 0.33) and the CC50 ratio (coconut meal fibers: corn cob fibers: durian peel fibers is equal to 0.50: 0.25: 0.25) can pass the standard in physical properties and mechanical properties. Moreover their fiberboards have good thermal insulation.