The aim of this study was to manufacture wood based particleboard by using wood particles and agricultural residues of walnut and almond shells that have no economical value other than being used merely as low grade fuel and fodder and evaluating of its performance. This study was done at two stages; first determination of optimum press condition of producing boards from mixture of wood particles and walnut/almond shells and second stage was evaluation of the effect of different ratios of walnut/almond shells (10 and 30%) and the shell mesh size (≤ 0.7 and ≥ 2 mm) on their mechanical (modulus of rupture and modulus of elasticity and internal bonding) and physical (thickness swelling and water absorption) properties. The result of first stage of the study showed that of press pressure of 2.5 and 5 MPa, press temperature of 150 and 180 °C and press time of 5 and 10 minutes, optimum press condition of producing boards from mixture of wood particles and walnut/almond shells are press pressure of 2.5 MPa, press temperature of 180 °C and press time of 5 minutes. The result of second stage of the study showed no meaningful difference between mechanical and physical properties of composite boards containing 10 percent of walnut and almond shell with reference one (board A). Besides, the range of used almond and walnut mesh size had no meaningful differences.