Abstract: Petrochemical project is a complex system engineering. there are many risks in the process of project implementation, which affect the project performance. From the perspective of project owner, for large-scale petrochemical project, the project performance is divided into two dimensions: process performance and Outcome Performance, and the measurement of project performance is extended to five dimensions: time limit, cost, quality, safety and environment, which breaks through the iron triangle for the measurement of project performance: time limit, cost, quality. Meanwhile, risk management is divided into risk management commitment, organization risk culture, risk identification ability, risk analysis capabilities and risk management standardization. Combined with the survey data of large-scale petrochemical projects in China, the relationship between risk management and performance for large-scale petrochemical project is studied by structural equation model. In addition, the moderating effect of technical complexity and organizational complexity on the relationship between risk management and project performance is discussed. The empirical research shows that the project risk management can improve the project performance, the higher level of the technical complexity and the organizational complexity, the effect of the project risk management on the project performance is more remarkable.