The discovery of cancer stem cells has improved our understanding of tumour occurrence and development. Colorectal cancer stem cells may be derived from mutations in normal intestinal epithelial stem cells. CD133+ and aldehyde dehydrogenase 1 (ALDH1)+ cells have strong tumorigenic capacities and may represent different subpopulations of colorectal cancer stem cells. Multiple signalling pathways, especially the Wnt pathway, are important in colorectal cancer occurrence and development, and maintaining the stemness of colorectal cancer stem cells. Identifying colorectal cancer stem cells and understanding the related signalling pathways are important for developing new targeted interventions for colorectal cancer.