Functional traits are genetic, relatively stable, and measurable parameters of organisms (plants, animals, and microorganisms), closely related to productivity optimization or environmental adaptation at the species level. With the development of ecology, functional traits have been increasingly used to reveal the adaptation, response, and optimization mechanisms of plants to the environment at different scales, including organs, species, functional types, communities, and ecosystems. Meanwhile, ecosystem ecology (or macroecology) should involve these rapidly developing functional traits and high-level observation technology to expand its application scope and scientifically reveal the response and adaptation of ecosystem structure and function to changing environments. However, linking traditional functional traits with these macro-technologies to resolve ecological problems and adapt to global change is challenging. The mismatch in scale and units between traditional functional traits and macroecological research are the primary problems. Macro-technologies, such as remote sensing, eddy-flux observation, and ecological modeling, are integrated at the community rather than at the species scales. To solve the gaps, researchers have attempted to develop a new concept named ecosystem traits (ESTs). ESTs are any measurable functional traits that can be standardized by unit land area at the community scale, typically in intensity or density, and can reflect the adaptation, reproduction, and productivity optimization of organisms (plants, animals, microbes, and others) to the environment. Theoretically, ESTs in any ecosystem are composed of plant, animal, and microbial community traits, which interact to complete multiple ecosystem functions. ESTs link traditional functional traits and macroecological technologies, particularly leaf traits of plant community traits, and provide a basis for integrating remote sensing and flux observations and model simulations into ecosystems. Furthermore, ESTs are valuable in exploring plant–animal–microbe interactions at the community scale. Notably, they provide a theoretical basis for constructing a new principle of ecosystem ecology using functional traits and developed a new framework of “structure–functional trait–function,” solving various challenges in future ecological studies on a large scale.