With the increasing developing of petrochemical engineering construction market, China has accumulated rich experience in project engineering management and cost control, but has not yet established a complete cost control performance evaluation system, and the traditional project cost control method has been unable to meet the cost requirements under the new project management environment. For this, this paper studies the engineering management and cost control system theory of petrochemical projects, and builds one petrochemical project cost control system. The analysis results show that mature project management mode has been increasingly applied in petrochemical projects. The construction of the engineering cost control early warning system can achieve the objective of cost control. The related cost control performance evaluation system can greatly improve the actual engineering cost control level and realize the quantification and standardization of cost control performance evaluation.