With the rapid development of our country's economy and the extension of urban road, the underground transportation provides convenience for people's travel, and shield tunnels have become an important part of the urban underground traffic infrastructure. As the weakest part of shield tunnel structure, segment joint is very vulnerable to earthquake damage in the vast territory of China. In order to explore the mechanical properties of segment joints under earthquake action, this paper takes a single layer lined segment joint of a certain subway line as the research object. The numerical model of the segment joint is established, and the mechanical properties under static action are compared and verified. Then the negative moment cyclic loading of the segment joint is carried out to study its seismic characteristics. Finally, the influence of bolt preload and joint axial force on the seismic performance of joints is discussed. The results show that: (1) The failure process of segment joint under cyclic loading of negative bending moment can be divided into three stages. (2) Cyclic loading significantly reduces the bearing capacity of the segment joints, and there are obvious damage accumulation characteristics such as decreasing strength and stiffness. (3) Axial force and bolt preload weaken the pinching effect of the joint hysteretic curve. The increase in axial force enhances the peak bending moment and ductility performance of the joint. But the influence of bolt preload is relatively small.