In the present study, linseed was fed to growing–finishing barrows for three different lengths of time before slaughter at 100 g/kg diet, and the dietary ALA content is calculated to 20 g/kg diet. The aim of this study was to investigate the effect of duration of dietary linseed feeding on subcutaneous carcass fat, intramuscular fat and the muscle mass. It was found that feeding a diet of 100 g of linseed/kg to pigs increased the content of n-3 polyunsaturated fatty acid in muscle and adipose tissue, stimulated intramuscular fat accumulation, and promoted the hypertrophy of the longissimus dorsi muscle, quadriceps femoris muscle mass, and semitendinosus muscle. Further research should be done to identify the effect of dietary n-3 PUFA enrichment in tissues on lipid metabolism related genes in adipose tissue and muscle, respectively.