Objective:To isolate and identify the chemical constituents in the whole plant of the Petasites japonicus

and to provide samples for activity screening. Method: The whole plant of P. japonicus was extracted with MeOH. And column chromatographic techniques were used and the structures of the constituents were elucidated on the basis of physicochemical properties and spectral data. Result: Five compounds were obtained and identified as valerilactones A ( 1 )

bakkenolide-Ⅴa( 2 )

bakkenolide-Ⅳa( 3 )

bakkenolide-Ⅲa( 4 )

homofukinolide ( 5 ). Conclusion: Compounds 1 were obtained from P. genus for the first time.Compounds 2

3

4 were obtained from the whole plant of P. japonicus for the first time.