Abstract: This study was conducted to investigate the effect of Metformin on PRKAG3 gene expression, growth performance and pork quality in pigs. 10 DLY pigs (80 kg) were randomly divided into control and experimental groups, pigs in experimental group fed diet supplemented with Metformin at dose of 400 mg·kg^-1 body weight. After 2 weeks, all pigs were slaughtered to determine growth performance, AMPK activity, PRKAG3 gene expression, AMPKγ3 protein levels and pork quality traits. The results showed that, compared with control group, experimental group had 13.92% higher AMPK activity (P<0.05), 4.39-fold PRKAG3 gene expression (P<0.05) and 35.53% higher AMPKγ3 protein level (P<0.05). Pigs in experimental group had 13.80% lower feed intake (P<0.05), 13.14% lower average daily gain and 6.67% higher F/G than that in control group. Experimental group reduced dressing percentage, lean percentage, eye lean area, and backfat thickness（P>0.05）, and significantly reduced carcass length(P<0.05). Compared with control group, experimental group had lower pH2, drip loss, a values, higher pH1, shear force and cooked meat percentage, but there was no significant difference between control and experimental groups（P>0.05）. Experimental group significantly increased L and b values (P<0.01). These results suggested that supplementary 400 mg·kg^-1 body weight Metformin in diet activated PRAKAG3 gene expression, which affected the growth performance and pork quality.