In this paper, the difference in thermal degradation behavior between polypropylene glycol (PPG) and its complex of β-cyclodextrin was carefully compared by a gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) as well as in situ Fourier transformation infrared spectroscopy and thermogravimetric (TG) analyses. The present data revealed a very interesting phenomenon that there was a variation in the order of thermal stability of PPG and its complex between the conditions of TG and GC-TOF-MS. In addition, the relative abundances of released fragments in the inclusion complex were changed with different programmed temperatures in GC-TOF-MS measurements. We believe that this work will provide a better understanding on the degradation behavior of polypseudorotaxanes.Graphical abstract:.