When a parallel arranging prestressed steel wire is used to strengthen concrete bending slabs, the cost is too high if the steel wire is covered with high tensile strength composite mortar. Aiming at this, a new strengthening method was proposed, in which was combined with pre-tensioning prestressing steel wire,and common high-strength cement mortar was used to replace post-tensioning the former mortar. This method can prestress on the tension zone of the concrete slab and cover the mortar layer. And the feasibility of the strengthening principle and construction technology were demonstrated by strengthening the experimental study and numerical analysis about the model test of a reinforced concrete bending slab, which shows that the premise is to spray epoxy interface agent on the joint surface in order to ensure that the joint surface does not produce detachment of the destruction. So this method can avoid using expensive high tensile strength composite mortar, the strengthening cost can be reduced, and the mechanical properties of cross-section after reinforcement can be enhanced.