Objective：To investigate the effects of omega-3 polyunsaturated fatty acids（n-3 PUFAs）on myocardial extracellular matrix remodeling in rats with myocardial hypertrophy after abdominal aortic coarctation（AAC）. Methods：Forty male Sprague-Dawley rats were randomly divided into sham operation group（group A）and model group. AAC was performed in model group. One week after operation，the model group was randomly divided into three groups：AAC group（group B），AAC + n-3PUFAs low dose group（group C），AAC+ n-3PUFAs high dose group（group D）. The group C and group D were given by gavage 400 mg/（kg·d）and 1 000 mg/（kg·d）n-3 PUFAs respectively，and the group A and group B were given an equal volume of normal saline. After 8 weeks，the rats were sacrificed，and the left ventricular mass index（LVW/BW）and cardiac mass index（HW/BW）were measured. The myocardial tissues were stained with HE and Masson. The serum hydroxyproline was determined by alkaline hydrolysis method. The content of matrix metalloproteinase-9（MMP-9），tissue inhibitor of metalloproteinase-1（TIMP-1）and fibronectin（FN）in myocardial tissue were analyzed by Western blot. Results：Compared with the group A，LVW/BW，HW/BW，and hydroxyproline content in groups B，C，and D increased significantly（P < 0.05）. Pathological staining showed cardiomyocyte hypertrophy，collagen fiber and MMP-9 expression increasing. The expression of TIMP-1 decreased（P < 0.05）. The expressions of FN in groups B，C and D were significantly higher than that in group A（P < 0.05）. Compared with group B，LVW/BW，HW/BW，and hydroxyproline content in group C and group D decreased，the myocardial cells shown less hypertrophy by pathological staining and the collagen content also decreased，and MMP-9 and FN expression decreased，whereas TIMP-1 expression increased（P < 0.05）. Compared with group C，the changes of all the above indexes in group D were greater（P < 0.05）. All these differences have statistical significance. Conclusion：n-3PUFAs have protective effects on myocardial hypertrophy after abdominal aortic coarctation. The mechanism may be related to the inhibition of overexpression of MMP-9 and FN，the up-regulation of TIMP-1 expression，and the influence on the changes in extracellular matrix components.