Chinese hamster ovary (CHO) cells play an irreplaceable role in biopharmaceuticals because the cells can be adapted to grow in suspension cultures and are capable of producing high quality biologics exhibiting human-like post-translational modifications. However, gene expression regulation such as transgene silencing and epigenetic modifications may reduce the recombinant protein production due to the decrease of expression stability of CHO cells. This paper summarized the role of epigenetic modifications in CHO cells, including DNA methylation, histone modification and miRNA, as well as their effects on gene expression regulation.