Abstract: A pot experiment was conducted to investigate the effects of UV-B radiation on sensitive index (SI) synthetically formed by the height, leaf area and biomass, and on the accumulation of rosmarinic acid (RA) and salvianolic acid B (SAB) of Salvia miltiorrhiza in two growth periods. The results showed the SI in the shoot vigorous growth and harvesting periods both decreased with the increasing UV-B radiation, but the SI in the latter period was even less. The RA and SAB contents in the leaves increased with the increasing UV-B radiation, and the increment was greater in the harvesting period than in the shoot vigorous growth period. The RA and SAB contents decreased in the roots, and decreased with the increasing UV-B intensity and duration. Total contents of RA and SAB in roots decreased to 10.0% and 6.3% of the control under the high UV-B intensity in the harvesting period.