The demand for plant foods (PFs) is increasing worldwide, partly because of considerations of sustainable development and environmental protection, and partly because PFs are an important part of the healthy dietary structure of the population and an important source of nutrients. Flavor substances of PFs give the food unique sensory properties and are an important factor influencing consumer preferences. This review focused on the flavor substances of PFs and systematically described their structural properties, including the key functional groups in the molecular structure. The biogenic flavor mechanisms were revealed in depth in terms of the roles of taste and olfactory receptors. Finally, current challenges were analyzed. This review addresses the lack of systematic exploration and in-depth evaluation of flavor substances of foods in the current food field, especially in plant-based foods, reveals the biogenic flavor mechanisms, and provides a comprehensive theoretical reference for in-depth research and development in the field of flavors of PFs.