This paper, proceeding from the project construction process, the management mode and the implementation way, makes an in-depth study of the environmental characteristics and the managerial elements of petrochemical engineering construction project, revealing the inherent laws, establishing a theoretical model, and proposing a theory of the mechanisms of construction project management; and presents profound revelations found for construction project management in petrochemical engineering in seven aspects, which can play a guiding role in improving the managerial performance of petrochemical construction project. The theory established proposes that: The construction project management in petrochemical engineering is a complex systematic process, formed of 5 phases and 55 sub-processes of management, and exposed to many factors of influence; the environmental characteristics and managerial elements exercise positive impacts on managerial performance, but different factors have different impacts and act in different ways on managerial performance; the managerial elements of petrochemical engineering construction project are tiered, transferable, systematic and quantifiable, and the role of managerial elements in the managerial performance can be systematically integrated, quantitatively explained and transferred in a multi-level way.