Bamboo composite is a kind of engineering composite bamboo with modern processing technology, high strength and quality ratio, environmental protection and beautiful appearance.For the research and application of bamboo integrated timber in China started late, the shear performance of the research is more complicated and less, in this paper, for the study of shear span ratio on lateral pressure bamboo integrated timber beams is influenced by shear bearing capacity, shear span ratio to change parameters, design the shear span ratio were 0.75, 1.0, 1.5, 2.0 and 2.5 of 5 groups (each group 3) bamboo integrated timber beams four-point bending test, the lateral pressure bamboo integrated timber beams under load deformation characteristics, failure forms and the influence law of shear span ratio, to explore the influence factors of bamboo integrated timber beam shear performance and its bearing capacity calculation method.The results show that the bamboo composite beams have higher bearing capacity and stiffness.The shear bearing capacity is related to the shear span ratio.There are two main types of failure modes. When the shear span ratio changes from small to large, the failure modes of bamboo composite beams change from interlaminar shear failure to bending failure.When the shear span ratio is less than 1.5, interlaminar shear failure occurs, while when the shear span ratio is greater than or equal to 1.5, bending failure occurs.The formulas for calculating the flexural bearing capacity, shear bearing capacity and elastic deformation of bamboo composite beams are put forward, which are in good agreement with the measured values.