Objective: To explore the preparative method and study the degradation characteristics of bone repair composite of DL-polylactic acid (PDLLA)/hydroxyapatite(HA)/decalcifying bone matrix (DBM) in vitro.Methods: An emulsion blend method was developed to prepare the composite of PDLLA/HA/DBM in weight ratio of PDLLA:HA:DBM=1.5-2:1-1.5:1. The dynamic changes of weight, biomechanical property and pH value of PDLLA/HA/DBM and PDLLA in phosphate buffered saline (PBS, pH 7.4) were studied respectively through degradation tests in vitro.Results: Without being heated, PDLLA, HA and DBM could be synthesized with the emulsion blend method as bone composite of PDLLA/HA/DBM, which had both osteoconductive and osteoinductive effects. The diameter of the aperture was 100-400 μm and the gap rate was 71.3%. During degradation, the pH value of PDLLA solution decreased lightly within 2 weeks, but decreased obviously at the end of 4 weeks and the value was 4.0. While the pH value of PDLLA/HA/DBM kept quite steady and was 6.4 at the end of 12 weeks. The weight of PDLLA changed little within 4 weeks, then changed obviously and was 50% of its initial weight at the end of 12 weeks. While the weight of PDLLA/HA/DBM changed little within 5 weeks, then changed obviously and was 60% of the initial weight at the end of 12 weeks. The initial biomechanical strength of PDLLA was 1.33 MPa, decreased little within 3 weeks, then changed obviously and kept at 0.11 MPa at the end of 12 weeks. The initial biomechanical strength of PDLLA/HA/DBM was 1.7 MPa, decreased little within 4 weeks, then changed obviously and kept at 0.21 MPa at the end of 12 weeks. Conclusions: The emulsion blend method is a new method to prepare bone repair materials. As a new bone repair material, PDLLA/HA/DBM is more suitable for regeneration and cell implantation, and the environment during its degradation is advantageous to the growth of bone cells.