This paper presents a three-dimensional nonlinear finite elemental analysis about the reinforcement concrete beams strengthened by bolting steel plate, which is a new strengthening method by anchoring plate to beam surface but not using any glue to help bonding. The contact effects between the steel plate with reinforced concrete beam surface was simulated by developing the contact elements. The effects of the plate thickness and the collocation of anchor bolts were investigated. The damage evolution about variable collocation of anchor bolts were investigated. It is declared that the collocation of anchor bolts play an obvious effects on the flexural capacity of strengthened beams, but the plate thickness give a little influence on it.