To reasonably evaluate the increase in deflection of PC beams after local corrosion, a calculation method for deflection of corroded PC beams based on the stress and strain model of corroded reinforcement was proposed by considering the beam-arch effect formed by reinforcement corrosion and the degradation of bond strength between reinforcement and concrete. Bending tests on a batch of locally corroded PC beams were carried out to verify the calculation method, and a parameter analysis on the corrosion rate and corrosion position was conducted. The results show that the load?deflection curves obtained by the calculation method are in good agreement with the experimental results. When the corrosion rate is less than 5%, the bending stiffness of the PC beams basically does not change; when the corrosion rate exceeds 5%, the weakening degree of the corrosion rate on the bending stiffness of the PC beams gradually increases, and the deflection of the corroded beams increases significantly with the increase of the corrosion rate. The influence of the corrosion position on the deflection is related to the corrosion rate; when the corrosion rate is relatively low, the change of the corrosion position has little influence on the deflection; when the corrosion rate exceeds 10%, the influence increases, and the mid-span is the most unfavorable.