Effect of the different ratio of succinic acid to cigarettes on the volatile substances formed in the process of pyrolysis was studied to investigate the influence mechamism of succinic acid on the decreasing flavor of cigarettes by the technologies of online Pyrolysis-Gas Chromatography/Mass Spectrometry. It was shown that free nicotine would decrease substancially while mono-protonated and diprotonated nicotine would increase obviously with increasing succinic acid. With the addition of 1%, 2% and 3% of succinic acid to cigarettes, the total volatile substances formed in the process of pyrolysis of cigarettes was reduced by about 23 percent, while low molecular weight carbonyls and furans down by 26%～30% and alkenes down by 23%～26%. The quantity of carbohydrates pyrolysates and volatile Maillard reaction’s products fell by 30 percent, particularly DDMP and 5-hydroxymethyl furfural decreased sharply, down by 84.1% and 75.6% respectively when the usage of succinic acid reached 3%. The total phenols were reduced by 29.5%, 37.0% and 37.3% respectively while key aroma chemicals fell by 31.4%, 36.8% and 36.8% respectively, when 1%, 2% and 3% of succinic acid were added to cigarettes. According to the changing conditions of the formed volatile substances, the influence mechanism of succinic acid on the suppressing flavor of cigarettes was deduced.