The authors made composite using crushed bamboo mat（Phyflostachys bambusoides） to investigate how board density affected physical and mechanical properties and what density would produce optimum performance.The results showed that increasing board density from 0.8 g/cm3 to 1.20 g/cm3 had a positive influence on the average width swelling,modulus of rupture（MOR）,modulus of elasticity（MOE） and horizontal shear strength.However,the high overall board density exhibited negative impact on board thickness swelling.