Field asymmetric ion mobility spectrometry(FAIMS)was used to distinguish moldy tobacco and normal tobacco.Tobacco ion peak characteristics from FAMIS analysis and a recognition rule were established.The key parameters for the moldy tobacco recognition in FAIMS included compensation voltage(CV),dispersion electric field(DF)and ion current value(ICV).When the DF and CV value were set as the followings: DF=50%,CV=-0.788 V,or DF=55%,CV=-0.882 V,the characteristic ion peaks of moldy tobacco tested under positive mode were observed.ICV values increased with the degree of moldy severity; therefore,the ICV values were used to distinguish moldy tobacco under DF and CV conditions described above.When the ICV values were <0.13 and <0.11 for each condition,respectively,samples were determined as normal tobacco; when the ICV values were 0.24>ICV≥0.13 and 0.20>ICV≥0.11,respectively,samples were determined as mild moldy; when the ICV values were≥0.24 and ≥0.20,respectively,samples were determined as severe moldy; when the ICV values were> 0.13 and <0.11,or <0.13 and> 0.11,respectively,the moldy condition could not be determined.These rules were applied to distinguish moldy tobacco among 65 types of tobacco samples.Among which,29 types of normal tobacco,22 types of mild moldy tobacco and 6 types of severe moldy tobacco were correctly identified,and 4 types of tobacco were not determined.The recognition accuracy rate was 93.4%.