Engineering is a construction activity and process to reform the nature under certain restriction (including decision. ,design, construction and evaluation), following necessary procedure, design documents,  regulations, rules and standards to integrate basic production elements and resource with specific related engineering science, engineering technology and management principles, its final result is an engineering body with predetermined functions. The essence of engineering is the sum of mass activities to utilize and reform the nature. The basic characters of engineering are integration, mass involved, dynamic and with agreement. The close relationship between engineering and science and technology expresses the incorporation of engineering and science and technology, as well as confluence,  unity and interaction of engineering with science and technology.