Hydrogen cyanide is one of the major ciliatoxic components in tobacco smoke.It is formed from pyrolysis of various nitrogenous compounds such as amino acids and nitrate in tobacco.In this study, ten nitrogen-containing compounds in tobacco were pyrolysed from 30℃ to 900℃, the formed hydrogen cyanide was absorbed by diluted sodium hydroxide and determined by ion chromatography.The cyanide content of absorption solution can be directly determined without complicated pretreatments.The whole procedure of determination could be completed in 9 min.The limit of detection (S/N =3) was 0.48ug/L and the relative standard deviation was 2.98% (n=6).The recovery of fortified blanks were 98% to 101.2%.This method has been applied to the determination of hydrogen cyanide from the pyrolysis of selected tobacco components and the mechanism of hydrogen cyanide formation from different nitrogenous compound has been discussed.