Plant community stability is the central ecological issue that underpins the structural integrity, functional continuity, and service sustainability of steppe ecosystems. Its influencing mechanisms have become a frontier focus in ecological and botanical research amid accelerating global climate change and intensifying anthropogenic activities. Building upon previous research, this review synthesizes current understanding of the theoretical connotation and characterization parameters of stability, the diversity-stability relationship, and the influencing mechanisms of plant community stability in steppe ecosystems. It further identifies critical knowledge gaps and provides an outlook on potential research priorities and development directions. Studies have shown that under the impacts of climate change and anthropogenic activities, the stability of plant communities in steppe ecosystems is collectively regulated by multiple biotic mechanisms—such as overyielding effects (via selection and complementarity), insurance effects, asynchrony, compensation effects, portfolio effects, and statistical averaging effects—along with abiotic factors such as soil nutrient availability. These mechanisms exhibit distinct ecosystem type specificity and significant spatio-temporal scale dependence. Future research needs to establish a systematic paradigm of “multiple disturbance factors-multiple regulatory processes-multiple spatio-temporal scales and organizational dimensions” to further unravel the intrinsic linkages between the structure, function, and stability of steppe ecosystems under global change, aiming to provide a reference for the sustainable development and adaptive management practices of steppe ecosystems.