The work aims to prepare toughened polylactic acid (PLA)-based sheets with oxidation resistance. The composite sheets were prepared with blended acetyl tributyl citrate (ATBC), polylactic acid and tea polyphenols (TP). The thermal properties and mechanical properties of the sheets were investigated by differential scanning calorimetry (DSC), the tensile strength and elongation at break were tested, the chemical interaction within the material was determined by Fourier infrared spectroscopy (FTIR), the hydrophilicity and moisture barrier were tested by water contact angle and moisture permeability, and the resistance to oxidation was tested by DPPH method. The elongation at break increased by 108.7%, while the tensile strength of the specimens changed irregularly. The infrared test showed a shift of C=O to lower wave numbers, and the addition of ATBC and TP effectively promoted PLA crystallization. Water contact angle tests showed that the surface of PLA before and after modification was hydrophobic, while the addition of TP resulted in a significantly more hydrophilic surface and a poorer water vapor barrier for specimens containing TP. The results of the oxidation resistance test showed that the oxidation resistance of the sheets with a mass fraction of 1% of TP was significantly increased, with an oxidation resistance equivalent to L-ascorbic acid (Vc) at a mass concentration of approximately 300 mg/L. Therefore, the ATBC/PLA-TP composite sheet has good properties and potential for development.