The effect of temperature on the chemical structure of polypropylene was studied using two-dimensional infrared spectroscopy. In the frequency range of 1500~1350 cm-1, the molecular structure of polypropylene was studied by one-dimensional infrared spectroscopy, second derivative infrared spectroscopy and fourth derivative infrared spectroscopy of C-H bending vibration（δC-H） . Two-dimensional infrared spectroscopy was then used to study the effect of temperature on the δC-H infrared absorbance intensity of polypropylene. The polypropylene δC-H mainly included methyl asymmetrical bending vibration mode (δasCH3), methyl symmetrical bending vibration mode (δsCH3) and methylene bending vibration mode (δ CH2). With increase of the measurement temperature, the sequence of intensity changes in the δ C-H infrared absorbance intensity of polypropylene was δ CH2-2（1464 cm-1）>δ CH2-1（1475 cm-1）>δ asCH3（1455 cm-1）>δ sCH3（1375 cm-1） . The study demonstrated the key roles of two-dimensional infrared spectroscopy in the analysis of thermal denaturation of the polymer packaging materials.