Posterior capsular opacification (PCO) is a major post-operative complication of cataract surgery. Epithelial-mesenchymal transition (EMT) contributes to PCO. We previously indicated that Wnt3a induces the EMT of human lens epithelial cells (LECs) and plays an important role in the development of PCO. The present study aimed to test the potential effect of Dickkopf-1 (Dkk1) on Wnt3a-induced cell migration and the EMT of LECs and to explore possible cellular mechanisms. The secretion of Dkk1 was reduced in the rabbit PCO model, and Dkk1 injected into the eyes post-surgical manipulation prevented PCO formation. Cultured HLE-B3 cells were then transfected with Wnt3a in the presence or absence of Dkk1. Dkk1 treatment restored the epithelial phenotype and reversed the expression of EMT-associated proteins induced by Wnt3a. Dkk1 suppressed LEC migration and the expression of matrix metalloproteinase-1 (MMP-1), and the activity of MMP-2 and MMP-9. Dkk1 inhibited the nuclear accumulation of β-catenin, which is the key regulator of the canonical Wnt signaling. Our results indicate that Dkk1 inhibits Wnt3a-induced migration and the EMT of human LECs.The results contribute to the prevention of PCO formation and development.