Isostasy is a fundamental concept in Earth Sciences, based on the idea that a lighter crust floats on a denser mantle. The emergence and development of isostatic theories (e.g., Punching Hypothesis and Elastic Plate Theory) and models (e.g., Airy model, Pratt model and Flexure model) are of great significance for the study of geodynamic processes, such as the rheological properties of the lithosphere, interactions between the Earth’s spheres and orogenesis. We summarized the isostatic theories, classical models and calculation methods and its application in tectonic geomorphology on variable spatial scales. These examples include the optimization of different glacier isostatic rebound models and its significance to the implication of global sea level change, clarifying the development process and restricting factors of seamounts and ocean islands, using the elastic plate models to reconstruct the history of mountain uplift and basin flexural subsidence and further exploring the interaction between them, constraining physical parameters of the earth according to the shoreline deflection, building the river delta development model to service in the modern social economy, revealing the relationship between the crust flexural deformation caused by reservoir impoundment and the development of geohazards, and coseismic landslides' influence on local landscape evolution. Finally, we discussed and prospected the future development direction of isostasy in tectonic geomorphology research, that is to solve the problems of key areas quantitatively by combining with high- precision geodesy and geochronology methods, and further study the interaction among surface processes, deep earth processes and dynamics, of the Earth’s spheres, comprehensively and systematically.