Abstract: In order to both keep the advantages of the RC beams strengthened with wire mesh-mortar or small diameter steel bar-mortar, and increase the load carrying capacity of the strengthened beams significantly, a thought to strengthen RC beams with steel bar/wire mesh mortar was advanced. Seven steel bars/wire mesh mortar-strengthening beams, and one comparative RC beam were produced for a comparison experimental study. The influences of the strengthening methods, and loading conditions on the bending behavior of the strengthened beams were investigated. The research result indicated that the steel bar/wire mesh mortar can significantly increase the moment capacity. Even though under a low reinforcement ratio of wire mesh the strengthened beams still have a good crack control property and displacement ductility. It was also showed that the moment capacity of once-loading beams has very small difference from that of the beams subjected to a preloading onto yield before strengthening. The calculation methods for predicting the moment capacity of the strengthened beams were also provided and show a good agreement with the tested results.