Abstract: By taking a simply supported composite beam under uniformly distributed load as an example,the redistribution of longitudinal shear force,induced by the plastic deformation of flexible connectors such as studs,was investigated.Based on the actual working condition of the connectors,the mechanical full-range of the interface of a steel-concrete composite beam was divided into elastic,elasto-plastic and failure stages.Simplified analytical models were established for every stage and corresponding formulae for calculating longitudinal shear force and axial force were derived.The research shows that axial force increases linearly with the increase of load when the redistribution is taken into account and load is less;then with the growth of load,the increasing is non-linear;lastly,it trends to be unchanged.