Composite materials with different contents of silicon-modified pineapple leaf fiber (PALF), calcined oyster shell powder (OSP), and poly(butylene succinate) (PBS) were successfully prepared. Moreover, the flexural performance of the composite materials containing calcined oxazoline (OSP) was obviously enhanced. The addition of silicon-modified PALF contributed to the improvement of the material's thermal stability and affected its water absorption performance. Significant degradation differences were observed in PALF composite materials modified with glycidoxypropyl trimethoxysilane (Glymo) and PBS when adding calcined OSP. Formulations containing calcined OSP and epoxy-type silicon-modified PALF showed better adhesion to the PBS substrate, thereby exhibiting good flexural performance. The flexural strength of the formulation increased by 47% compared to pure PBS. This research accentuates the differences between epoxy-type silicon-modified PALF and PBS when integrated with calcined OSP. Biodegradation experiments demonstrated a notable 38.32% degradation after 105 days of the soil burial period. Furthermore, the study investigated the potential for manufacturing products, including tableware, storage boxes, and bowls, using injection molding techniques.