The infrared spectra of Gutta-Percha with different degree of crosslinking have been measured at room temperature and by heating. It was discoveredthat 5 special peaks corresponding to deformation vibration at low wave numberregion have disappeared by heating but are not effected by the change Df crosslinking degree eventhough the crystalline in Gutta-Percha has disappeared completelyand it has changed into a high elastomer at high degre of crosslinking. Thus wemay deduce that the existance of 5 special peaks should be relative to theconfor-mation regularity of the chain segments between crosslink junctions in network of Gutta-Percha.