We found that lnc-RBMY2FP was specifically expressed in 5 male patients' tumor tissues, while lnc-RBMY2FP was not detectable in compared adjacent non-tumor tissues, nor in the other 10 male patients or female patients. Lnc-RBMY2FP enhances HCC cell growth, proliferation and tumor stemness both in vitro and in vivo. Mechanistically, lnc-RBMY2FP interacts with DNMT1 and hampers its binding onto promoters of RBMY gene family. Thus, maintenance of promoter methylation status is disturbed because of inhibition of DNMT1 activity, leading to increased expression of RBMY1A1 protein and enhanced hepatocarcinogenesis.