The protective effect of curcumin on p38 MAPK/NF-κB signaling pathway on myocardial fibrosis induced by prolonged and intensity exercise in rats was studied.SPF male SD rats were randomly divided into control group (C),model group (M),and curcumin + model group (CM).Group C received quiet feeding,while the other groups received increasing load treadmill training for 6 weeks.During the period,group CM was given a gavage of curcumin,while the other groups were given a gavage of with 0.5% sodium carboxymethyl cellulose of the same volume.The samples were taken to observe the morphology and ultrastructure of the myocardium,and detect the serum and myocardial biochemical indexes 24 h after the training.The results showed that compared with group C in myocardial tissue morphology,there were injurious changes,myocardial fiber fracture,inflammatory infiltration and connective tissue hyperplasia in group M,the improvement was more obvious in group CM than that in group M;myocardial ultrastructure,mitochondrial cristae of group M shortened,part of them appeared vacuolar degeneration,there was no obvious abnormality in group CM.Compared with group C,glycogen volume fraction of myocardial tissue,cTNI,TGF-β1,TNF-α,IL-1β,p-p38 MAPK and NF-κB p65 in myocardium increased significantly(P<0.01);Compared with group M,glycogen volume fraction of myocardial tissue,cTNI,TGF-β1,TNF-α,IL-1β,p-p38 MAPK and NF-κB p65 in myocardium decreased significantly(P<0.05 or P<0.01).These results suggested that curcumin may inhibit the over-activation and expression of the related proteins in p38 MAPK/NF-κB signaling pathway,balance the synthesis and secretion of inflammatory factors,and the synthesis and degradation of ECM in myocardial tissue,then alleviate myocardial fibrosis.