Abstract: In order to study the difference and major influencing factors of hydrocyanic cyanide release of flue-cured tobacco in mainstream smoke, the flue-cured tobacco at three stem positions from five main producing areas in China were selected as the test material. The release amount of hydrocyanic cyanide and chemical component contents were determined, and their relationships were studied by using correlation analysis, multiple linear regression, and path analysis. The results showed that the release amount of hydrogen cyanide in mainstream cigarette smoke was significantly different among producing areas. The amount in Huanghuai area was significantly higher than others. The release amounts of hydrogen cyanide in mainstream cigarette smoke of unblended flue-cured tobaccos leaves at different stem positions were also significant, upper leaves >middle leaves >lower leaves. Chemical components of flue-cured tobacco leaves had huge influence on hydrogen cyanide release in mainstream smoke. Hydrocyanic cyanide release positively correlated with alkaloids, volatile alkali, ammonia, total nitrogen, amino acids and other nitrogenous substances, malonic acid and chlorine;while negatively correlated with total sugar, reducing sugar and ratio of potassium to chloride. Regression analysis and path analysis results showed that the main factors affecting the release amount of hydrocyanic cyanide in cigarette mainstream smoke was as follow: the total nitrogen >total alkaloid >praline >ammonia >chlorine. A regression model of hydrocyanic cyanide release in mainstream cigarette smoke was established, which could explain 61.3% of the variation in the dependent variable. Other influencing factor is required to establish more accurate prediction model.