Abstract: The flexural property of RC beams with high-strength steel wire mesh and polymer mortar overlay is analysed, and a unified formula is proposed for design of strengthened beams made of different materials. It is shown that the ultimate flexural capacity and the crack resistance property of the strengthened beam are greatly influenced by the initial stress state of the original beam and the U-style strengthening. An ultimate flexural capacity calculation formula for the RC beams with high-strength steel wire mesh and polymer mortar overlay is obtained by the limit equilibrium method on the normal section. Based on the concrete structure design codes, modified calculation formulas of crack width and crack space are obtained. The calculation results agree well with the test values.