With the rapid development of the new generation of information technology, the fourth industrial revolution with green intelligence as the core is quietly emerging, bringing great challenges and opportunities for the traditional petrochemical industry. The construction of intelligent plant is the way to transform and upgrade petrochemical enterprises. The strategic goal of automation of production, informationization of management and intelligence of enterprise can be achieved and digital transformation and intelligent development can be realized by building refining intelligence capability in the aspects of comprehensive perception, safety control, production intelligence, plant-wide optimization and efficient operation. Combining with the construction example of the intelligent plant of Changqing ethane to ethylene project, this paper discusses the digital application in the construction of intelligent plant in petrochemical enterprises.