Abstract:Three diterpenotd alkaloids were isolated from Aconitum sinomontanum var. angustius distributed in south Gansu. They were identified as ranaconitine(Ⅰ), lappaconitine(Ⅱ), 3-acetylaconitine(Ⅲ) on the basis of spectral evidences(UV, IR, HNMR, 13CNMR, MS).