Objective To explore the distribution and accumulation regularity of catalpol in leaves during the growth of Rehmannia glutinosa var. huechingensis. Methods HPLC method was used to determine the catalpol content in fresh medicinal materials with acetonitrile-water (0.6:99.4) as the mobile phase and 210 nm as detection wavelength. Regression equation was Y = 377.26X - 1. 054 3. The water contents of the leaves at different developmental stages were also determined, so that the catalpol content could be achieved on dry matter basis.Results Both leaves and root tubers contained catalpol. The content of catalpol in leaves rised up to peak rapidly in August or September and then degraded gradually until leaves wither and fall. The content of catalpol in root tubers increased with the growth of root tubers and reached peak until harvest. Conclusions The variation of catalpol is caused by the physiological regulation of plants. The leaves contain a considerable amount of catalpol. Further study is needed to benefit the comprehensive utilization of Rehmannia glutinosa Libosch.