To improve the prefabrication of concreteConcrete slabs, facilitate the recyclability of steel-beam, and minimize on-site construction pollution, a demountable composite-beam system equipped with a conical tube bolted shear connectorShear connectors was proposed. The mechanical properties of the demountable conical tube bolted shear connectorShear connectors were evaluated through push-out tests. Experimental results indicate that the ultimate displacement reached 9.68 mm. Finite element models (FEM) were developed and validated against test results from conical tube bolted shear connector push-out programmes. Based on the validated FEM, the flexural behaviorFlexural behavior of steel-concreteConcrete composite beamComposite beams with the conical tube bolted shear connectorsShear connectors were investigated. The influences of steelSteel grades, shear-connection degree, bolt strength and concreteConcrete strength on the initial flexural stiffness, load-deflection and bearing capacity were systematically assessed. In general, the steelSteel grades and shear-connection are crucial to the flexural behaviorFlexural behavior of steel-beam composite beamComposite beams. A 55% reduction in shear‐connection degree results in a 2% decrease in ultimate flexural capacity, and a 21% increase in ultimate deflection. The research findings might provide references for practical design of steel-concreteConcrete composite beamsComposite beams employing conical tube bolted shear connectors.