DNA methylation as one kind of major epigenetic modifications is highly conserved in eukaryotes. The dominant type of DNA methylation is 5-methylcytosine (5meC) which can occur in three different cytosine contexts in plants, CG, CHG and CHH (H represents C, A or T). DNA methylation play important roles in multiple cellular processes in both plants and animals, including development, disease and stress responses. DNA methylation is commonly associated with heterochromatin marks and exerts negative effect on gene expression. Recent studied revealed that DNA methylation can also function as functional module to positively regulate gene expression. My talk will focus on the regulatory network of DNA methylation in plants, some recent findings about its roles in gene expression and crop development.