To study the effect of fermented barley extract with Lactobacillus plantarum dy-1 （LFBE） on insulin resistance in high-fat diet （HFD）-induced obese rats. We induced the obese rat model by feeding high fat diet， then treated these rats with LFBE （1 000 mg/kg bw） and water （4 ml/kg bw） respectively for 8 weeks， and determinated the levels of body weight， serum lipid profiles and insulin levels， glucose tolerance and others. LFBE could reduce the body weight， the levels of serum lipid profiles and insulin， improve glucose tolerance. So， LFBE could lower rate of increase of obese rats’ body weights， reverse the disorders of glucose metabolism and ameliorate the symptoms of insulin resistance in obese rats. At the same time， LFBE can inhibit expression of pro-inflammatory factors and the NF-κB and the JNK/p38 mediated MAPK signaling pathway in obese rats， and then ameliorate the symptoms of insulin resistance. The mechanism was related with LFBE can inhibit the phosphorylation of MAPK and NF-κB.