Objectives. The aim of this study was to test the effects of collagen external scaffold (CES) in intimal hyperplasia of vein grafts and explore its underlying mechanisms. Methods. Thirty-six New Zealand white rabbits were randomized into no-graft group, graft group, and CES group. The rabbit arteriovenous graft model was established. In CES group, the vein graft was wrapped around with CES. The hemodynamic parameters of vein grafts were measured intraoperatively and 4 weeks after operation by ultrasonic examination. Histological characteristics of vein grafts were also evaluated 4 weeks later. The mRNA and protein levels of proliferating cell nuclear antigen (PCNA), active cleaved-caspase-3 (ClvCasp-3), and smooth muscle 22 alpha (SM22..) were measured 4 weeks later by quantitative real-time PCR and western blot. Results. CES significantly improved the hemodynamic stability of vein grafts, with higher blood velocity and blood flow. Similarly, CES also markedly mitigated intimal hyperplasia and inhibited dilatation of vein grafts. In CES group, the upexpression of PCNA and ClvCasp-3 and the downexpression of SM22.. were inhibited. Conclusion. CES exerts beneficial effects in mitigating intimal hyperplasia and improving remodeling of autogenous vein grafts, which may be associated with reducing the proliferation and apoptosis and preserving the phenotype of VSMCs.