4-{[2-(Methoxycarbonyl)phenyl]amino}-2-methyl-4-oxobutanoic acid amide, the diterpenoid alkaloid delavaine B, and the new talassamine-type alkaloid 15-epinaviculine B were isolated for the first time from the aerial part of Delphinium oreophilum Huth. The structures of the compounds were elucidated using 1D and 2D NMR spectroscopy, mass spectrometry, and an X-ray crystal structure analysis for the new alkaloid. The stereochemistry of the talassamine framework and H-bonds in the crystal of 15-epinaviculine B were analyzed.