Objective To study the expression of NF-κB in rats' liver after welfare impaired by restraint stress.Methods SD rats, ±170 g, male and female half, welfare were impaired by restraint stress. Body weight gain and food consumption were recorded throughout the study, mRNA and protein expression of NF-κB p65 in liver were detected after the study finished by real-time quantitative PCR and Western blotting.Results Compared with the control group(group C), the body weight gain and food efficiency ratio(FER) of restraint group(group R) were decreased(P<0.01), but mRNA and protein expression of NF-κB p65 were much higher(P<0.01). Compared with female, mRNA and protein expression of NF-κB p65 of male rats were much higher in group R(P<0.01), but showed no significant difference in group C(P>0.05). Conclusion After welfare impaired, the expression of NF-κB in rats' liver are much higher than before. It shows that NF-κB has effects during the process of welfare being impaired.