A single-cavity dual-electrode discharge cavity and an excimer laser including such a discharge cavity are disclosed. The discharge cavity may comprise a cavity body and two sets of main discharge electrodes. The cavity body may comprise a left chamber and a right chamber arranged to form a symmetric dual-chamber cavity. The left and right chambers can interface and communicate with each other at a plane of symmetry of the entire discharge cavity. The two sets of main discharge electrodes can be disposed in the left and right chambers on the upper side, respectively. According to the present disclosure, the single-cavity configuration can be used to achieve functions of dual-cavity configurations, such as MOPA, MOPO, and MOPRA. Thus, it is possible to reduce system complexities and also ensure synchronization of discharging in the discharge cavity.