Abstract: The mechanical properties of SRC beams strengthened with FRP (fiber reinforce polymer) are further investigated theoretically including its failure mechanism and loadability, based on earlier theoretical works on RC beams. The nonlinear stress diagram of the concrete in the state the stress is lower than its ultimate value is transformed into an equivalent rectangular stress diagram, then the relevant parameters m and n are given equivalently. And the correlation equation of flexural capacity on the cross section of SRC beam strengthened with FRP is deduced according to different types of failure. The equation is expressed clear, simple and easy to application. The depth of relative boundary compressive region and the boundary disposition rate of FRP are both given in view of different failure types.