Twin-screw extrusion using a co-rotating 32-mm extruder was applied to disperse microcrystalline cellulose(MCC) and / or wood flour (WF) in poly(e-caprolactone)(PCL).A series of composites were placed in three different environmental conditions for sixty days.The mechanical property was evaluated by the test of tensile strength, modulus, and impact resistance.The loss in mechanical properties after thirty days and sixty days has been studied to illuminate the durability of different composites.The weight gain of samples in water submersion was measured periodically to investigate the hydrophilic properties of composites.