Anti-obesity effect of Pteridium aquilinum and its mechanism was investigated by measuring its inhibitory effect against 3T3-L1 preadipocyte differentiation and high fat diet induced C57BL/6J obese mice. The differentiation of 3T3-L1 cells was induced and Oil Red O staining was used to analyze the effect of Pteridium aquilinum ethanol extract （PAE） on the differentiation of 3T3-L1 preadipocytes. To elucidate the mechanism of PAE， we performed Western blot for the expression of genes related with adipogenesis （PPARγ， CEBPα， SREBP-1c） and lipogenesis （FAS， ACC）. C57BL/6J mice were induced by high fat diet for 6 weeks. Obese C57BL/6J mice were then randomly divided into high-fat diet group （HFD） and the 1%PAE group （HFD+PAE）. In addition， C57BL/6J mice fed with normal diet were selected as the normal diet group （ND）. After 8 weeks， the body weight， glucose metabolism indications （blood glucose， glucose tolerance） and serum lipid levels （TG， TC） in all mice were evaluated. The results showed that PAE suppressed 3T3-L1 adipocyte differentiation and reduced the accumulation of fat in adipocytes. Treatment of PAE markedly suppressed the protein expression of PPARγ， CEBPα and SREBP-1c， as well as FAS and ACC （P<0.05）， which are the key transcription factors and metabolic enzymes in adipogenesis and lipogenesis. After 8-weeks feeding， the indicator in HFD group were high than ND group， including body weight， body fat deposition， serum glucose and serum lipid （P<0.05）. Treatment with PAE significantly decreased the body weight， blood glucose and the levels of serum TC， TG. PAE also effectively improved impaired glucose tolerance （P<0.05）. In conclusion， Pteridium aquilinum suppressed 3T3-L1 adipocyte differentiation， inhibited obesity， hyperglycemia， hyperlipemia and improved impaired glucose tolerance in C57BL/6J obese mice. These effects might be closed related to its inhibition of genes expression regulating adipogenesis and lipogenesis.