Abstract: Spandex is a polyurethane elastic fiber known for its wide range of applications. A large amount of spandex waste is generated during the production process, which needs to be recycled. Because the filature oil of the spandex waste would block the spin system during the production process, to control the content of filature oil before the spandex waste is recycled is necessary. In this paper, a new method to determine the residual oil content in spandex waste is established using the pyrolysis gas chromatography-mass spectrometry. The method is simple, efficient, and without any sample pretreatment, the method can provide accurate and reliable residual oil data for the cleaning work of spandex waste, especially for the industrial cleaning purpose.