Abstract: Based on the model of truss theory, taking the influence of the mechanical behavior of corroded reinforcements, the thickness of a steel plate, the bond strength, and the thickness of a cover on the capacity of beams into accounts quantitatively, a calculation method for the ultimate load-carrying capacity of corroded RC beams strengthened by steel plates anchored with studs is proposed. The theory model is verified by conducting tests on 9 RC beams strengthened by steel plates anchored with studs, and by 3 corroded RC beams and 3 strengthened RC beams without corroded reinforcements. Experimental results and theoretical results show that a 1mm increase in the thickness of a steel plate will result in 15kN~20kN increase in bearing capacity under same cover thickness and a close corrosion rate, and under the situation of different corrosion rates, an increase in the corrosion rate of 2%~3% of results will cause a decrease in bearing capacity about 10kN.