Abstract: Emergy analysis is a science created by H.T.Odum.Emergy,specifically,Solar Emergy,is "the available solar energy used up directly and indirectly to make a service or product".Odum pioneered the development and use of emergy.He presented it as a way of understanding the behavior of self-organized systems,valuing ecological goods and services,and jointly analyzing ecological and economic systems.This basic concept is quite straightforward,however,its implications potentially profound.This paper discusses the main progress of the science of emergy on its applications and theory,provides insight into the relationship between it and other ecological analysis methods,attempts to point out research difficulties,and suggests areas for further studies in order to promote and better understand it.

Key words: Ecological system, emergy, ecosystem evaluation, transformity