The structure composition and working situation of hollow plank of bamboo timber combination has been expounded in detail, and the mechanical calculation model about hollow plank of bamboo timber combination has been established.With structure mechanical theory of composite material the bending deformation of hollow plank of bamboo timber combination acted by crosswise force has been calculated analytically.Meanwhile the level that the shearing force has exerted an influence on bending deflection has been analysed.In order to test and verify whether the theoretical analysis is rational or not,the practical deflection of reality structure has been measured.The results indicate that deflection calculated on theory were on the whole the same as that ones obtained under practical measurement.