The principle of electrochemistry is adopted in this test. The current is switched on 7 RC beams strengthened with CFRP of different measures (include: not strengthened L-0, strengthened with one layer of CFRP on the bottom L-1, coated only with epoxy resin L-2, strengthened with one layer of CFRP on the bottom and coated with epoxy resin on the lateral L-3, strengthened with two layers of CFRP on the bottom L-4, strengthened with one layer of CFRP on the bottom and alternately on the lateral L-5, strengthened with CFRP entirely L-6) when the beams are working in corrosive environment. So the corrosion speed of the beams becomes fast. Comprehensive comparison of mechanical property and transformation rule among them has been made. The different effects of the enhancement in durability are analyzed and its reason is researched. The test results indicate that the durability of the beams strengthened with CFRP can be enhanced significantly especially in the beam strengthened with CFRP entirely L-6.