Abstract: The constitutive equation of the bamboowood composite materials that utilized bambooparticle and woodfiber as materials was established based on the theory of elasticity mechanics. The forecasting models of the elasticity modulus of the composite materials in the main directions and any directions were established. The forecasting models could show the relation between the ratio of bambooparticle and woodfiber and the elasticity modulus of this composite materials. The error between the forecasting models and the results obtained by experiments was about 14％—77％. The forecasting models can be used to design the materials and structure of the composite materials by bambooparticle and woodfiber.