By use of Guangzhou temperature and NCEP reanalysis data from 1951-200 5, the change of Guangzhou temperature and its probable cause is studied. Eviden ce suggests that Guangzhou temperature shows an obvious increase since the middl e of 1980s, with the most prominent trend in winter minimal temperature. The num ber of low temperature day (≤5℃) in winter decreases obviously and that of hig h temperature day (≥35℃) in summer increases prominently. Results also show th at the increase in Guangzhou temperature has a direct relationship with the heig ht of 500hPa fields and the weakening of winter and summer monsoon. And the r ole of urbanization process can’t be neglected in the increase of Guangzhou tem perature, especially in winter minimal temperature.