Green tea leaves contain anti-cancer antioxidants which can be used in drug, food, hygienic and cosmetic products. In this article, the extraction mechanism and kinetics of these components are investigated. Therefore, Diffusion coefficients of C, EC, EGC, EGCG and Caffeine of Iranian green tea leaves in water were calculated. A two diffusion coefficient model (slow and fast) was used for mass transfer modeling of the system. According to the results, the intra-particle diffusion step is the rate-controlling step of the extraction process. Furthermore, the optimum extraction conditions (temperature and time) of these components were determined as the following: Caffeine (80oC, 20 min), C (90oC, 80 min), EC (80oC, 20 min), EGC (80oC, 20 min) and EGCG (90oC, 20 min).