A OSB webbed bamboo I-shaped joist connected and fixed by epoxy resin adhesive and nails was presented. The web height, shear span ratio and web stiffener were included as control parameters to see their effect on the flexural performance of 24 OSB webbed bamboo joists. The failure process, failure mechanism, deformation and carrying capacity were investigated and the shear capacities were also discussed. The results show that the composite joists show excellent combination performance, higher stiffness and strength. Also, the shear capacity of this joist has a close relationship with the shear span ratio and web height. When the shear span ration is less than or equal to 2.0, the failure modes were characterized by shear compression failure of the OSB web panels. The web stiffeners can markedly improve the ultimate load of the joists by 3.4%~38.0%, and is helpful to ultimate displacement and initial flexural stiffness by 1.7%~12.6% and 10%~30%, respectively. The web is higher and the growth is greater.