Abstract: Objective To develop the bone-implanted calcium sulfate/polylactic acid/gentamycin（CaS/PLA/GM） delivery system using composite of citrated calcium sulfate and polylactic acid as an antibiotic delivery matrix and to evaluate its biocompatibility. Methods CaS/PLA/GM implant tablets were made from composite of citrated calcium sulfate and polylactic acid mixed with gentamycin at a certain ratio. According to ISO 10993-1 standards,following biological experiments were performed to evaluate the biocompatibility and safety of the CaS/PLA/GM delivery system,as well as haemolysis,cytotoxicity,pyrogenic,and intramuscular implanting tests. Results The haemolysis rate was 3.07%,which was lower than the positive standard for haemolysis. The drug delivery system had no toxicity to mesenchymal cell proliferation. The body temperature had no significant changes in pyrogenic test. The drug delivery system could be absorbed when it was implanted in muscles,and no significant inflammatory response was observed in the surrounding tissue. Conclusion The CaS/PLA/GM system is biocompatible and safe. It can meet the demands of medical biomaterials.