The biodegradation of biodegradable polymers is influenced not only by their chemical structure but also by their formulation and environmental conditions. In this study, poly(butylene succinate) (PBS) was selected as a model biodegradable polymer to systematically investigate the combined effects of formulation and degradation environment. PBS samples with different morphologies including pellet, powder, filament, film, and nanofiber) were prepared to vary specific surface area (SSA), and their biodegradation behaviors were evaluated under compost, soil, and marine sediment conditions. The results revealed that both formulation and environmental conditions play critical roles in governing PBS biodegradation. A clear correlation between SSA and degradation behavior was identified, with higher SSA accelerating degradation. Furthermore, linear relationships were observed between biodegradation extent and degradation progression across key stages, including the lag phase, intermediate stage, and final stage. The overall degradation rate varied significantly depending on environmental conditions, with the fastest degradation observed under compost conditions. In addition, PBS samples recovered at intermediate and final stages were physicochemically characterized, and linear regression analysis was employed to quantitatively correlate biodegradation extent with key parameters, including functional group, molecular weight and thermal properties. These findings highlight the coupled influence of material form and environmental context on biodegradation behavior, while providing complementary insights through the correlation between degradation extent and physicochemical changes. This study offers practical guidance for predicting degradation performance and designing biodegradable polymers under realistic disposal scenarios.