Abstract: Abstract: The electricity consumption accounts for about 20% to 30% of total energy consumption in a petrochemical enterprise. The optimal power flow analysis can guide electricity workers to optimize the operation mode of the enterprise power network, reduce the power loss and improve the power, which can save the energy and costs of the enterprise maximized. It can also provide scientific basis for decision making to workers considering the economy of power supply grid during making network planning in order to develop a rational power network planning. Keywords: Optimal Power Flow, petrochemical enterprise, interior point method, PSASP 1. Brief of Optimal Power Flow An Optimal Power Flow (OPF) is an optimal technique in a power system and is a type of power flow calculation method for ensuring the economic and safe operation of a power system. It uniformly coordinates the economic dispatch, quality control, and safe operation of a power network, and plays an important role in the planning and operation of a power system. An OPF can be used to uniformly consider the requirements of a power system with respect to the safety, economy, and voltage quality. In addition, it is a necessary analytical method in modern power generation and management. 2. Algorithm of Optimal Power Flow 2.1 The Newton method The Newton method has a good convergence and fast convergence speed, and is able to be used in optimisation calculations for large-scale power networks. However, it may be based on human experience when dealing with an inequality constraint, which is mainly expressed as the functional inequality constraints needing to be determined according to human principles, and the penalty factor of various variables (voltage, transformation ratio of transformer, and power) also needing to be given by human users. 2.2 The interior point method The interior point method is a combination of the Newton method, Lagrange function method, and logarithmic barrier function method. It has good convergence and a fast convergence speed, and is able to be used in optimisation calculations of large-scale power networks. Because the solution of the interior point method is always the interior point of the constraint conditions, which has no obvious treatment process for inequality constraints, determining the functional inequality constraints necessary for the Newton method is therefore avoided. 3. Overview of Power Grid Operation in Petrochemical Enterprises The processing of crude oil is the main line of production process in a petrochemical enterprise. The electricity consumption accounts for about 20% to 30% of total energy consumption in a petrochemical enterprise. The main loads are fans, compressors and pumps which are driven by large motors. 4. The Introduction of PSASP Power System Analysis Software Package(PSASP) is a resource sharing and easy to use computing power system analysis software. 5. Optimal Power Flow Analysis of a petrochemical enterprise The optimal power flow analysis based on the interior point method and PSASP is used to analyze the operating condition in the distribution network of an oil refinery and petrochemical enterprise. 6. Conclusion The application of the OPF system shows that the system can quickly calculate the technical indicators of OPF. Evaluation system of indicators is complete, which can be used to evaluate the optimization results from various angles. The system can guide workers to optimize the operation mode of the enterprise power network, reduce the power loss and improve the power factor, so that the energy and costs of the enterprise can be minimized. It can provide scientific basis for decision making to workers considering the economy of power supply grid during making network planning in order to develop a rational power network planning.