In order to promote the application of bolt fasteners with diameters of up to 10 mm in steel-wood composite structures, the effects of the number of transverse rows of bolts, bolt diameters and longitudinal spacing of bolts on the bending performance of steel-wood composite beams were investigated. By designing a composite beam with a I-steel beam at the lower part and wooden board at the upper part, the upper and lower parts connected by bolts. A three-point bending load test was carried out on 8 test beams, to observe the failure mode, mid-span deflection variation, mid-span section strain and slip effect at the steel-wood intersection at the end of the beam respectively, to investigate the effect of different bolt parameters on the flexural mechanical properties of the steel-wood composite beam. The test results showed that the main damage mode of the steel-wood combination beam is the mid-span deflection up to 1/27 of the calculated span, resulting in deformation damage; Composite beams had high flexural capacity and ductility coefficient. The maximum relative slip at the steel-wood interface of each specimen was 2-6 mm; Among the parameters of bolt arrangement, the longitudinal spacing of bolts had greater influence on the strain difference at the steel-wood interface in the span of the composite beam, while the bolt diameter had less influence. The concept of bolt area ratio of steel-wood composite beam was proposed, i.e. the ratio of total bolt area to compressive area of wood board. With the increase of the bolt area ratio, the flexural load capacity of the specimen increases significantly and the maximum slip at the intersection decreases gradually, although the displacement ductility coefficient decreases. The range of bolt could be quickly calculated by optimum the reasonable range of bolt area ratio, which provides design reference for practical application of such steel-wood composite beam.