The rising utilization of PLA/PBAT-ST20 presents potential ecological risks stemming from its casual disposal and incomplete degradation. To solve this problem, this study investigated the degradation capabilities of PLA/PBAT-ST20 by a co-culture system comprising two thermophilic bacteria, Pseudomonas G1 and Kocuria G2, selected and identified from the thermophilic phase of compost. Structural characterization results revealed that the strains colonized the PLA/PBAT-ST20's surface, causing holes and cracks, with an increase in the carbonyl index (CI) and polydispersity index (PDI), indicating oxidative degradation. Enzyme activity results demonstrated that the co-culture system significantly enhanced the secretion and activity of proteases and lipases, promoting the breakdown of ester bonds. LC-QTOF-MS results showed that various intermediate products were obtained after degradation, ultimately participating in the TCA cycle (ko00020), further completely mineralized. Additionally, after 15-day compost, the co-culture system achieved a degradation rate of 72.14 ± 2.1wt% for PBAT/PLA-ST20 films, with a decrease in the abundance of plastic fragments of all sizes, demonstrating efficient degradation of PLA/PBAT-ST20 films. This study highlights the potential of thermophilic bacteria to address plastic pollution through biodegradation and emphasizes that the co-culture system could serve as an ideal solution for the remediation of PLA/PBAT plastics. Environmental implicationAs a biodegradable material, PLA/PBAT-ST20 film is now widely used in shopping bags to package food waste. An urgent problem has emerged on how to degrade PLA/PBAT-ST20 film quickly and effectively. Two thermophilic bacterial strains, Pseudomonas G1 and Kocuria G2, were isolated from compost and co-cultivated to efficiently degrade PLA/PBAT-ST20 film in both medium and compost environments. These results revealed the potential of thermophilic co-culture system in composting. This study provides a new perspective on the biochemical degradation of PLA/PBAT-ST20 and a new approach to solve the actual contamination of PLA/PBAT-ST20 in the composting process.