Abstract: 3D nanofiber scaffold composites in bone tissue engineering are promising. Poly(L-lactic acid)-polycaprolactone-cellulose acetate 3D composite micro-nanofibrous porous scaffolds were prepared by low-temperature phase separation, without the assistance of additives. The effects of PCL-CA-PLLA ratio, quenching time, polymer concentration and quenching temperature on the morphology of fibrous scaffolds were investigated by SEM. The diameter of PCL-CA-PLLA (1∶1∶8) is (276±121) nm, which is similar to the size of the extracellular matrix (50-500 nm), and the porosity and specific surface area are 95.12% and 54.18 m²/g, respectively. It is indicated that PCL-CA-PLLA 3D micro-nanofibrous porous scaffold composites are 3D porous materials with high porosity and large specific surface area. Compared with pure PLLA fibrous scaffolds, the mechanical strength and hydrophilicity of PCL-CA-PLLA 3D micro-nanofibrous porous scaffold composites are improved. PLLA-PCL-CA 3D micro-nanofibrous are expected to be ideal tissue engineering scaffold materials.