Two new bis-C(20)-diterpenoid alkaloids, bulleyanines A and B (1 and 2), were isolated from Aconitum bulleyanum. Their structures were elucidated by comprehensive spectroscopic analyses including UV, IR, MS, 1D and 2D NMR. Biological activity tests indicated that compound 1 exhibited significant inhibitory activity against nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW264.7 macrophages with the inhibition rate of 74.60% (40 mumol/L), while positive control dexamethasone gave 78.70% inhibition at 100 mug/ml.