Abstract: A case study of building models concerning delayed coking by using Petro-SIM desktop refining simulation software to optimize delayed coking operation and the whole refinery is introduced. Results show that models set up by Petro-SIM software not only can optimize the operation of single device and combined unit, but also to implement the desktop management of enterprise. In this case using Petro-SIM model to optimize the operation parameters of absorption-stabilization system of delayed coking unit, the C3 content in dry gas could be lowered significantly reducing economic loss; with Petro-SIM whole process simulation model, adjusting the recycle ratio of delayed coking unit from 1.15 to 1.08, the product distributions of whole refinery would be improved, providing an enhanced economic benefit of 8.9 MRMB annually by calculation.