Abstract: The pyrolysis characteristic study of dibutyl phthalate (DBP) at different temperatures was performed under anaerobic conditions. The quantitative analysis of the pyrolysis products was researched by GC/MS. The relationships of some products and pyrolysis temperatures were discussed. The main pyrolysis products of DBP are 2-butene, 1-butanol, and the component is complex with the increase of temperature, when the temperature is below 650 ℃. Phthalic anhydride and butyl benzoate are pyrolysised into smaller mass radicals, and polycyclic aromatic hydrocarbons such as phenanthrene, anthracene are found at 700 ℃. These characteristics are helpful for the environmental protection in study of recovery and reuse of plastic by pyrolysis.