Abstract: Objective To investigate the feasibility of repairing sciatic nerve in rats by acellular allogeneic nerve transp lantation treated with chondroitinase ABC-PLGA microspheres． Methods Chondroitinase ABC-PLGA microspheres were prepared by double emulsion methods． Forty adult male SD rats were randomly selected and divided into four groups (n=10): freeze-thrawed combined optim ized acellular nerve (FTOAN) group treated with chondroitinase ABC-PLGA microspheres (Group A), autologous nerve transp lantation group (Group B), FTOAN soaking chondroitinase ABC group (Group C), FTOAN treated with normal saline group (Group D)． Ten millimeters of nerve from the right sciatic nerve of animals in three groups (Group A, C, D) was artif cially cut and transp lanted with FTOAN． Group A and C were soaked in PBS, while group D were soaked in PBS solution containing 2 U/ml ChABC (pH 7．4)． Preparation line nerve of group C was taken by animals in group A and allograft nerve grafts were taken in both two groups, the outer membrane was sutured without tension, and preparated chondroitinase ABC-PLGA microspheres accounting for 0．2 µl was injected in the transp lanted neural segments from the seam s of proximal part of 2 mm, 4 mm, 6 mm, 8 mm respectively．Outer membrane suture was taken by group B on the right side of 10 mm broken sciatic nerve after inversion． Preparation line nerve of group D was taken by animals in group C and nerve-grafting was taken in both tw o groups． Group D made allograft nerve grafts with preparation line nerve of group A, and equal amount of isotonic saline was injected according to the position of group A． Gross specimen was observed 4, 8, 12 weeks after operation． Electrophysiological detection, HE staining, silver staining, electron microscope histological detection and image analysis were compared 12 weeks after operation． Results The preparated chondroitinase ABC microspheres had smooth surface and sphere uniform sizes, and no adhesion and clusters were found． W eibull equation curve show edthe stability of in vitro release of chondroitinase ABC-PLGA microspheres． The axonal regeneration of neural defect in rats could be promoted by freeze-thrawed combined optim ized acellular nerve group treated with chondroitinase ABC-PLGA microspheres, the quality and speed of nerve repairing were also improved． The regeneration nerve was thicker in diameter and lighter in adhesion．Electrophysiological detection and histology observation showed that all indicators were better than the two compared groups, and also the repair effect was much closer to autologous nerve grafts． Conclusion Freeze-thrawed combined optimized acellular nerve group treated with chondroitinase ABC-PLGA microspheres can repair the nerve injury in rats．