The extreme surcharge is an important factor that threatens the safety of shield tunnel structures. Besides， the deterioration of shield tunnel performance caused by reinforcement corrosion may aggravate the risk of structure damage under extreme surcharge. Therefore， an analysis method was proposed to evaluate the fragility of corroded shield tunnels under extreme surcharge. In this paper， a three-dimensional finite element model was established to simulate a corroded shield tunnel under extreme surcharge， taking some typical shallow buried shield tunnels located in soft soil as an example. A large number of numerical calculations were carried out considering the uncertainty on the coefficient of stratum resistance and gravity of soil. Then， the joint opening was taken as the index of fragility， and the fragility curve of the corroded shield tunnel under extreme surcharge was established through a two-parameter lognormal distribution model. This research studied the influence of extreme surcharge and corrosion rate on the fragility of shield tunnels. It showed that the fragility of the shield tunnel increased with the increase of extreme surcharge or corrosion rate of reinforcement； when the surcharge was light， the corrosion rate of reinforcement had a greater influence on the fragility of the tunnel； under the same work condition， compared with the joint located at the top or the bottom of the tunnel， the joint at the waist may have a higher probability of damage.