A kind of novel poly-L-lactide (PLLA)/β-calcium metaphosphate (β-CMP) fracture-fixation composite rod was prepared by a two-step compression-molding method. The in vitro bioactivity of the composite rod was evaluated by investigating the effects of dissolved products from the composite rod on osteoblasts. In addition, the in vitro biocompatibility of the composite rod was evaluated by an osteoblast adhesion-and-proliferation assay. The products from composite rod dissolution significantly promoted cell growth. Furthermore, osteoblasts adhered and spread well on the rod. This PLLA/β-CMP composite rod has potential applications for clinical use following the assessment of adaptation during in vivo studies.