Objective To investigate influence of preservation of remnant ligament on vascularization of grafts in anterior cruciate ligament (ACL) reconstruction.Methods Seventy-eight New Zealand rabbits were involved and both knees of the rabbits received one-stage ACL reconstruction simultaneously.One knee was reconstructed with preservation of residual fibers (remnant preservation group),and the contralateral one was treated with conventional debridement of residual fibers (remnant removal group).Blood flow of grafts was evaluated in vivo by laser doppler flow meter,expression of CD34 in vessels of grafts was measured by immunofluorescence method,growth of vessels surrounding grafts was observed with ink perfusion under stereomicroscope at 6,12,18,and 24 weeks after reconstruction.Results Laser doppler flow meter showed blood flow of grafts was significantly larger in remnant preservation group than in remnant removal group (P ＜ 0.01).Immunofluorescence testing revealed positive expression of CD34 of grafts was notably higher in remnant preservation group than in remnant removal group (P ＜ 0.05).Ink perfusion showed that the number of vessels surrounding grafts was much more in remnant preservation group than that in remnant removal group (P ＜ 0.05).Conclusion Remnant preservation benefits the vascularization of grafts in early stage after ACL reconstruction.