A new azaanthracene alkaloid, named 1-aza-4-(4 '-hydroxybenzyl)-9,10-dimethoxydioxolobenzo-2-oxo-1,2-dihydroanthracene (1), together with seven known azaanthracene alkaloid derivatives (2-8), were isolated from Corydalis decumbens for the first time. Their structures were elucidated by their spectral data and references. Compounds 1-8 were evaluated for their antidepressive activities by inhibiting reuptake of tritiated serotonin ([H-3]-NE and [(3H)]-5-HT) in rat brain synaptosomes. Among them, compounds 1 and 2 showed moderate antidepressive activities.