Autologous arteriovenous fistula (AVF) is commonly placed for hemodialysis treatment.Recent studies show that increased baseline serum level of Chitinase-3-like protein 1 (CHI3L1) is independently associated with a higher risk of the early failure of forearm AVFs.However, the changes and mechanisms of CHI3LI in local vascular tissues of failed AVF haven't be revealed. This study aims to conduct the expression and mechanism of CHI3L1 in vascular tissues from patients. Immunoreactivity of CHI3L1, matrix metalloproteinase 2 (MMP-2) and vascular endothelial growth factor-A (VEGF-A) were detected in vascular tissues collected from nine patients of AVF surgery. Due to the significant stenosis clinically, six of the nine patients received arteriovenous fistula reconstruction. The expression differences of CHI3L1 between the initial vascular tissues and failed AVF are significant (P ＜ 0.05). Failed AVF due to stenosis shows intraluminal thrombus, collagen fiber rupture, fibrous connective tissue hyperplasia, tube wall thickening, neovascularization, scattered inflammatory cell infiltration in the tunica media as well as high CHI3L1 expression level, and the expression of MMP-2 (r=0.9022, P=0.0139) and VEGF-A (r=0.8355, P=0.0393) was positively correlated with CHI3L1. CHI3L1 expression in vascular tissues possibly plays an important role in AVF failure. MMP-2 and VEGF-A may participate in venous stenosis with CHI3L1.