Abstract: Objective To analyze the results of external environment monitoring on avian influenza A (H7N9) virus in Guangzhou city of Guangdong province form 2013 to 2015,and to provide references for the prevention and control of human infection with H7N9 virus.Methods Totally 9 536 swab samples were randomly collected in regular intervals at live poultry retail outlets and wholesale markets,poultry farms,poultry free-range farmers,and wild migratory bird habitats in 12 counties or districts of Guangzhou municipality between February 2013 and May 2015.Nucleic acid of H7N9 avian influenza virus was detected with real-time fluorescent quantitative PCR.Results For all the swab specimens,the overall positive rate of H7N9 avian influenza virus was 3.13% and the yearly positive rates were 0.28%,4.57%,and 2.02% in 2013,2014,and 2015,respectively.Higher H7N9 avian influenza virus positive rates were observed for the samples collected at sampling sites in Yuexiu,Tianhe,Huangpu,Nansha,and Liwan district and for the samples collected during the 13th week (15.76%),15th week(23.84%),and 28th week (30.00%) of 2014.The positive rate of H7N9 avian influenza virus was 3.65%and 1.34% for the samples collected at live poultry retail outlets and wholesale markets and there were no positive samples were detected among the samples collected at poultry farms,poultry free-range farmers,and wild migratory bird habitats.The highest H7N9 avian influenza virus positive rate was 4.38% for the swab specimens of slop pail,sewage,and ground; the positive rates were 3.34% and 1.67% for the swab samples collected from terrestrial birds (chicken) and waterfowls (ducks and geese).Conclusion Contamination of H7N9 avian influenza virus exists in external environments involved in poultry raising and live poultry selling;live poultry retail outlets and wholesale markets are the sites with higher risk of human H7N9 avian influenza virus infection in Guangzhou municipality.