After the degradation of the plastic using various means, the most important part is to know the by-products produced due to the action of the microbes employed for the degradation of the plastic. After knowing the degradation products, only the significance of the method can be suggested. In literature various chromatographic techniques are available to analyze the by-products of the degraded plastic. In case of gas chromatography-mass spectra (GC-MS) method, the polythene degradation products were harvested using diethyl ether as a solvent. After employing the GC-MS technique, the obtained peaks were identified using the mass spectral libraries associated with the GC-MS software. In the present chapter, an attempt was made to discuss all the reported methods to analyze the degradation products of the plastic followed by the list of compounds identified based on the library search.