Plant functional traits are a series of core properties closely related to growth, survival, and reproduction, and usually have important ecological significance. Currently, trait-based studies have rapidly expanded to many fields of ecological research. Submerged macrophytes are an ecological group closely related to water and have influential effects on the structure and function of shallow lake ecosystems. Previous research on functional traits has mainly concentrated on terrestrial woody plants, with submerged macrophytes (also a type of grass) rarely reported. In this study, we compared the differences in functional traits between submerged macrophytes and terrestrial plants, and summarized the current research on the functional traits of submerged macrophytes based on several important problems in the study of terrestrial plants. We propose that functional traits can be used to guide the restoration of degraded freshwater ecosystems under the current changing global climate.