Abstract: Based on young leaves of Catharanthus roseus (L.) G. Don, callus is induced on the solid medium of MS+NAA 0.5 mg/L +2,4-D 0.5 mg/L +6 BA 2.0 mg/L. Two groups of callus are cultured in the dark and light, respectively. The influeces of light on the cell growth and physiological and biochemical characteristics are studied. The results show that: both the cell growth curves are like "S", and their growth circles are about 27 days. Activities of peroxides (POD) and superoxide dismutase (SOD) show two peaks. We also find that the alkaloid production increased during the growth circles and can get the most production at the 27th day.