After operation of the metro, there has been increasing longitudinal nonuniform settlements of shield tunnel due to various interior and exterior factors, and then some expansion of shield tunnel segment joint develops to varying degrees, which seriously impacts on the safety of the train. Taking geometric dimension of segment, curvature radius, stiffness ratio in longitudinal, uncertainty and epistemic uncertainty into consideration, an interval Monte Carlo method has been developed which combines simulation process with the interval analysis to estimate the probability of shield tunnel segment joint failure. Finally, the interval of the failure probability is obtained. Case studies are presented to discuss the effect of different curvature radius and stiffness ratio in longitudinal on the failure probability. Herce, the control sphere of the two factors is obtained under the certain interval of the failure probability. The results provide the guidance for tunnel protection，waterproof design and construction technique of shield tunnel.