This study was conducted to investigate the effects of antibacterial peptide agent (ABPA) on meat quality, contents of free amino acids and microelements in breast muscle of barred plymouth rock chickens. Using a single factor design, a total of 450 one-day-old barred plymouth rock chickens were randomly allocated to 3 groups with 3 replicates per group and 50 chickens (half male and half female) in each replicate. The experiment lasted for 90 days. Chickens in group Ⅰ (control group) were fed a basal diet, and the other chickens in groups Ⅱ and Ⅲ were fed with the basal diet supplemented with antibacterial peptide (ABP) and antibacterial peptides plus yeast (ABPY), respectively. The results showed as follows: 1) compared with the control group, drip loss in groups Ⅱ and Ⅲ had a decrease tendency, but there was no significant difference (P>0.05). The muscle fiber diameter in groups Ⅱ and Ⅲ was significantly lower than that in control group (P<0.01). The muscle fiber density in groups Ⅱ and Ⅲ was significantly higher than that in control group (P<0.05, P<0.01). 2) The contents of essential amino acids and total free amino acids in breast muscle in groups Ⅱ and Ⅲ had no significant difference compared with the control group (P>0.05). 3) The selenium content in groups Ⅱ and Ⅲ was significantly higher than that in the control group (P<0.01), and the manganese content in group Ⅲ was significantly higher than that in the control group (P<0.05), but the other microelement contents in groups Ⅱ and Ⅲ had no significant difference compared with the control group (P>0.05). In summary, ABPA has positive effects on meat quality, contents of free amino acids and microelements in breast muscle of barred plymouth rock chicken, and the use of ABPA is better than the using ABP alone.