In this paper we take the medicinal plants Catharanthus roseus as materials, the photosynthetic physiological, nitrogen metabolism and alkaloid metabolic process under different intensity UV-B radiation and soil drought environment were studied.We analysed the alkaloids metabolism to UV-B and drought response from the dynamic changes of carbon and nitrogen metabolism. The environmental factors to increase alkaloid content of Catharanthus roseus were also summarized and discussed. The results may provide som...