Abstract: The paper analyzes the physical-chemical behaviors of paraffin hydrocarbon, cycloparaffinie hydrocarbon, aromatic hydrocarbon and alkene and their functions in products, as well as the impact of aromatic hydrocarbon to antidetonating quality, anti-oxidation stability, burning performa nce, carbon-producing behavior, cetane number and thermal value of products. The analytical results show that the high-content aromatic hydrocarbon of products will pollute environment and reduce the working efficiency of engine. Suggestions and measures to rationally reduce the content of aromatic hydrocarbon in products are given.