Alternative stable states refer to two or more stable states in an ecosystem under the same external conditions. Ecosystems with alternative stable states respond to external conditions changes nonlinearly and hysteretic, with forward and backward regime shifts occurring at different environmental levels (thresholds). The region between the two thresholds is unstable, and the eventual ecosystems state depends on the initial conditions. Alternative stable states mainly result from positive feedback generated by various biotic-biotic and biotic-abiotic interactions in the ecosystem. For degraded ecosystems with alternative stable state, the recovery trajectory is not the same as the collapse, and feedback makes it more difficult to restoration. In the context of global change, it is expected that the frequency of catastrophic regime shifts and alternative stable states under climate change and human disturbance may increase. Therefore, incorporating the frameworks of ASS into restoration practices, and understanding when, how, and why to apply them is increasingly important. Here, we summarized the alternative stable states in the different ecosystems, the field and theoretical work in generating, diagnosing, and evaluating alternative stable states. It is generally believed that hysteresis, threshold, and positive feedback are important characteristics of alternative stable states. When putting the alternative stable states framework into restoration, correctly identifying the recovery threshold is still needed. On this basis, disrupting the feedback reinforcing the degraded state or strengthening the restoration feedback artificially to restore the ecosystem to the ideal state is a direction that restoration ecology should make efforts.