The invention relates to isopentenyl toluylene and application thereof in preparing medicine for treating inflammatory diseases. The isopentenyl toluylene is a new compound separated from Artocarpus styracifolius Pierre which is a plant of moraceae artocarpus, the compound is named as (+/-)-styracifolius phenol A, and the structure is shown in the description. The compound has strong inhibitory activity on respiratory burst of rat PMNs, the IC50 of the compound is 2.62+/-0.35 muM, and the compound can be further used for preparing the medicine for treating the inflammatory diseases, and used for clinical treatment of various kinds of oxidative damages such as rheumatoid arthritis, compensatory anti-inflammatory response syndrome, and systemic inflammatory response syndrome caused by excessive activation of the PMNs.