Biodegradable polyester-based bone substitutes are widely used in tissue engineering and regenerative medicine. This study aimed to provide insights for the development of novel bone substitute materials by enhancing the performance and practicality of existing systems. Using polylactic acid ( PLA ) and polyhydroxybutyrate ( PHB) as raw materials, nano-hydroxyapatite ( nHA ) was incorporated to modify the composite. The mechanical and degradation properties were tailored by adjusting the PHB content, while ensuring compatibility with 3D printing technologies. PLA / PHB / nHA composite filaments and scaffolds were successfully fabricated. Mechanical testing demonstrates that all parameters meet the application requirements. Increasing PHB content results in a moderate decline in mechanical properties but significantly improves the degradation capacity. The composite achieves the fastest degradation rate at a PHB content of 30% . Compared to conventional PLA, this material exhibits superior biocompatibility and degradation controllability. Cytotoxicity assays confirm a cell viability exceeding 90% for all compositions, without observed rejection.