DNA methylation, an important epigenetic modification, plays essential roles in plants and animals during their growth and development, and has attracted extensive attentions for the epigenetic researches in recent years. However, the functional roles and regulatory mechanisms of DNA methylation in development, and environmental response of insects remain unclear. In this paper, we reviewed the diversity and structure of the insect DNA methylation transferases, the function and regulation mechanisms of DNA methylation, as wellasthe methodologies in DNA methylation researches targeting on insects, in the hoping of shed lights on further understanding of the epigenetic regulation mechanism of insects and other arthropods.