The highly fatal avian influenza is a disease of fowl erupted in China and the nearby areas from the end of 2003 to the beginning of 2004, during which millions of domestic fowls were infected, and even .several people were infected and died. By means of contrast analysis method, an analysis is made of the variation of weather situation, temperature, humidity and wind speed during the time period, and it is found that low temperature and high humidity weather persisted in Guangzhou from the middle January to the beginning of February 2004 while avian influenza erupted. It is concluded that low temperature and high humidity are favorable for the occurrence and prevailing of the avian influenza, but increasing temperature and sunshine restrain the avian influenza.