Field-flow fractionation, hold great promises as a branch of chromatography to improve separation of macromolecules, particles and colloids ranging from 1 nm up to100 μm. This paper presents the concept, theory and varieties of field-flow fractionation, including thermal field-flow fractionation, sedimentation field-flow fractionation and electrical field-flow fractionation, and also gives a better understanding of how to utilize these technologies as well as to provide appropriate technical solutions to environmental issues. Our argument also raises the bottleneck in miniaturization and commercialization of filed-flow fractionation. Furthermore, field flow fractionation, couple with many analytical techniques, can be adapted to a wide range of applications. With the development of integration techniques in acoustics, optics and magnetics, a portable field-flow fractionation instrument which serves the environmental monitoring will come true.