Objective To investigate the role of vitamin D in the synthesis and degradation of aggrecan in rat articular chondrocytes at cellular level. Methods Rat articular chondrocytes were stimulated by IL-1α, IL-1β and TNF-α, respectively. Normal and inflammatory chondrocytes were treated with different doses of vitamin D, respectively. CCK8, Flow cytometry, real time-PCR and western blot analysis were used to examine the proliferation activity and apoptosis level of chondrocytes, and the expression of aggrecan, ADAMTS-4 and ADAMTS-5 at both mRNA and protein levels. Results IL-1α,IL-1β and TNF-α significantly decreased the proliferation activity and increased the apoptosis level of the chondrocytes. Furthermore, IL-1α, IL-1β and TNF-α significantly decreased the expression of aggrecan, and increased the expressions of ADAMTS-4 and ADAMTS-5 at both mRNA and protein levels in the chondrocytes. 1α,25(OH) ₂ D ₃ supplementation significantly increased the proliferation activity and decreased the apoptosis level of chondrocytes stimulated by IL-1α, IL-1β and TNF-α in a dose-dependent manner, but not affected the normal chondrocytes. Meanwhile, 1α,25(OH) ₂ D ₃ also significantly increased the expression of aggrecan, and decreased the expressions of ADAMTS-4 and ADAMTS-5 at both mRNA and protein levels in the chondrocytes under inflammatory conditions. Conclusions Vitamin D may promote the anabolism of aggrecan and inhibit aggrecanase activity in chondrocytes under inflammatory conditions, which may impact overall protection for articular cartilage.