Abstract: Objective：To explore the effect of vascular endothelial cells (EC) in the repair of long sciatic nerve defect in rats using acellular nerve allograft (ANA). Methods：Totally 80 female Sprague. Dawley rats were used in this study, of which 20 rats were sacrificed for the harvest of bilateral sciatic nerves as acellular nerve allograft and prepared according to Hudson's method. The remaining 60 rats were transected on the right sciatic nerve a 1.5 cm defect and evenly divided into three groups, ANG for autologous nerve graft using flipped sciatic nerve, ANA for acellular nerve graft alone, and ANA+EC for ANA loaded with EC. At 1, 2, 4 and 12 weeks after operation, 5 rats from each group were selected for tests including sciatic functional index (SFI), LDR, nerve conduction velocity recovery rate (NCVRR), complex muscle action potential recovery rate (CMAPRR), max traction force recovery rate (MTFRR), gastrocnemius muscle wet weight recovery rate (MWRR) and microvessel density proliferation rate (MVDPR). The nerve fibers, myelin thickness, G ratio and electron microscopic examination were performed at 12 weeks after operation. Results：At early stage after surgery, ANA+EC group showed an increase in SFI and MVDPR compared to ANA group (P<0.05). At later stage after surgery, ANA+EC group showed an increase in CMAPRR, MTFRR, MWRR compared to ANA group (P<0.05). ANA+EC also exhibited more similar morphology to ANG in the long term. Conclusions：In the treatment of long sciatic nerve defect rat model, muscle function is superior in the short term when using ANA+EC compared to using ANA alone. In the long term, the amount and quality of nerve fibers in ANA+EC is more comparable to that in ANG. Thus indicates the possible effect of improvement of nerve regeneration in vascular endothelial cells.