Abstract: Soft soils are widespread in megacities of China, they may account for 21% of the national GDP, soft soils characterized by high water content, high compressibility and low shear strength, and often require ground improvement to satisfy engineering requirements. Preloading method is one of the most commonly adopted methods for soft ground improvement, which involves installing prefabricated vertical drains (PVDs) to shorten drainage paths and accelerate pore water dissipation, thereby enhancing soil strength and reducing post-construction settlement. However, conventional PP/PE PVDs hardly biodegradable in soil, so they may retain drainage capacity after the preloading stage. This can result in an undesirably high rate of post-construction settlement. To address this issue, the research team has developed a novel biodegradable PVD based on a PLA/PBAT blend. This study involves conducting a series of laboratory accelerated degradation tests under simulated environmental and temperature conditions, in order to systematically quantify the deterioration of the macroscopic mechanical and hydraulic performance of PLA/PBAT PVDs during degradation. The results indicate a strong positive correlation between performance decay and degradation time, with higher temperatures leading to faster deterioration. Furthermore, specimens subjected to soil burial matrix experienced more significant reductions in compressive buckling strength and discharge capacity compared to those immersed in solution. Further correlation analyses revealed that molecular weight, discharge capacity and compressive buckling strength remained strongly and consistently interrelated across different conditions. These findings provide a basis for the durability-oriented design of biodegradable PVDs for use in soft ground improvement, offering important implications for controlling post-construction settlement.