Abstract: According to the rules of thermal cracking reaction of heavy oil and the basic principle of single event method, based on delayed coking process, the article introduces how to express molecular structure and thermal cracking reaction through Boolean relation matrix and assistant vector, and accordingly how to set up primary reaction network of single molecule on computer with the example of 2,5-dimethylnonane. The work shows that single event method can quickly and effectively set up single molecule primary reaction network on computer which build the base of setting up molecular level of (kinetic) model for delayed coking.