Abstract: Concrete structure strengthened with carbon fiber reinforced plastic sheet(CFS) is a new retrofit method in the field of civil engineering. Three reinforced concrete beams and four pre-stressed concrete beams have been tested under fatigue load after they are strengthened with CFS. Based on experimental results, the strengthened beam's strength and rigidity don't decrease after 2 million fatigue loads, and the peeling and brittle rupture of sheet don't happen, which proves the reliability of the CFS in practice. The calculation formula of bending bearing capacty of the strengthened beam that is accord with railway standard have been proposed, whose calculated values show good agreement with the experimental data.