As a medium among pregnant women, environment and fetus, placenta owns powerful and delicate epigenetic processes to regulate gene expression and maintain cellular homeostasis. N6-methyladenosine (m(6)A) is the most prevalent modification that determines the fate of RNA, and its dynamic reversibility indicates that m(6)A may serve as a sensitive responder to environmental stimuli. Emerging evidence suggests that m(6)A modifications play an essential role in placental development and maternal-fetal crosstalk, and are closely related to gestational diseases. Herein, we summarized the latest techniques for m(6)A sequencing and highlighted current advances of m(6)A modifications in maternal-fetal crosstalk and the underlying mechanisms in gestational diseases. Therefore, proper m(6)A modifications are important in placental development, but its disturbance mainly caused by various environmental factors can lead to abnormal placentation and function with possible consequences of gestational diseases, fetal growth and disease susceptibility in adulthood.