3-oxo-α-ionol-β-D-glucopyranoside and 7,8-dihyd-3-oxo-α-ionol-β-D glucopyranoside were isolated from flue-cured tobacco by traditional column chromatographic technology and high performance liquid chromatographic(HPLC) method.The structures were confirmed by ESI MS，1H NMR and 13C NMR.To develop thermally stable flavor，Py-GC-MS was used to measure the pyrolysis products at 300,600,900 ℃ in the helium environment.The main pyrolysis products were megastigmatrienones，3-oxo-α-ionol. The pyrolysis mechanisms of two glycosides were discussed.The thermal decomposition behavior of 3-oxo-α-ionol-β-D-glucopyranoside was firstly studied by thermal analysis coupled with IR and GC-MS(STA-IR-GC-MS) at 265 ℃.The results showed that STA-IR-GC-MS could be used to identify the main decomposition products of glucopyranosides conveniently and quickly.This method provides an accurate and quick way for the isolation and identification of thermal decomposition products of natural products.