An alkaloid compound, lappaconitine Hydrochloride, was synthesized with lappaconitine which was isolated from the root of Aconitum sinomontanum Nakai in Gansu province in China. The structures were elucidated by IR, NMR, Anal. and X-ray diffraction analysis. Crystal data: C32H47ClN2O9, Mr = 639.17, space group monoclinic, P21; a=10.665 (7) Å, b=12.178 (7) Å and c=12.214 (7) Å; β=91.003 (10)°, Z=2, Dx = 1.338 mg/m-3, F(000)= 684, µ=0.18.00 mm-1, V=1586.1 (16) Å3; R1=0.038, wR2=0.087, Flack parameter x= -0.12 (7). Ring A, B, C, D, E and F respectively present boat, chair, envelope, boat, boat and envelope forms. The absolute configuration was determined as 1S, 4S, 5S, 7S, 8S, 9S, 10S, 11S, 13R, 14S, 16S, 17 R. And the analgesic potential has been investigated in a mouse model of acute pain. The result exhibited that the analgesic effect of the compound is worse than lappaconitine hydrobromide.