Tremendous poly(ethylene terephthalate) (PET) plastics has been abandoned into the environment as rubbish, which is inert and accumulated in the ecosystem across the globe. In the present work, PET plastics are changed into PET particles through a sample low temperature solvothermal treatment, which is applied as anode material of lithium ion battery. The redox peaks in the positive and negative scanning of CV (Cyclic Voltammetry) are 0.9 and 1.1 V, respectively, and the reversible capacity is about 200 mAh/g at current density of 100 mA/g. The DFT (Density Functional Theory) calculation results shows that the inserted lithium ion is coordinated with two oxygen ions, which are on the two neighboring chains, respectively, and per formula of PET (C10H8O4) could store two lithium ions, he. the theoretical capacity is 279 mAh/g. The calculated redox potential is also consistent with the experimental results. The ex situ XRD (X-ray Diffraction), FTIR (Fourier transform infrared) and XPS (X-ray photoelectron spectroscopy) measurement results in the charge/discharge are consistent with DFT calculation results, and confirm that demonstrate that the polymer's lithiation/delithiation process is revisable. The present work provides a novel way to utilize the PET plastics waste.& para;& para;Significance: Innumerable PET plastics have been abandoned, which is resistance to natural degradation. Here the PET plastics were transformed into PET particles after a solvothermal treatment, of which the size was in the range from several microns to tens of microns. The PET particles were tested as the anode material of Lithium ion battery, and its reversible capacity is about 200 mAh/g at 100 mA/g. The energy storage mechanism is attributed to redox reaction between the inserted lithium ions and the ester groups on PET chain, which is confirmed through the DFT calculation and XRD, FTIR and XPS measurement results. This is the first report for PET plastics used as electrode materials, and it provides a new way to utilize the PET refuse.