To evaluate the potential ecological risks of heavy metals in sediment of large and medium\|scaled reservoirs in Guangdong province, the contents of Cu, Zn, Pb, Cd and Cr in sediments of 45 reservoirs were analyzed. The results showed that Cu, Zn, Pb and Cd contents in sediment were higher than the soil background values of Guangdong province except for Cr. The mean concentrations of Cu, Zn, Pb and Cd in sediment of reservoirs in northern area of Guangdong province were the highest which was 89.7, 321.21, 154.95 and 1.46mg/kg, respectively, followed by those in eastern and central areas, and the lowest in western area, however, Cr content was the highest in sediment of reservoirs in western area which was 130.81mg/kg. The enrichment factor of Cd was the highest in sediment of reservoirs in eastern and northern areas while that of Cu was the highest in sediment of reservoirs in western and central areas. In general, the potential ecological risk of heavy metals in sediment of reservoirs was very strong in northern area of Guangdong province, moderate in eastern and central areas, and slight in western area. The potential ecological risk of heavy metals in sediment of large and medium\|scaled reservoirs in most areas of Guangdong province resulted from high potential ecological risk factor of Cd in sediment. Anthropogenic activities, especially mining, were the main reason for elevated potential ecological risk of heavy metal in sediment of large and medium\|scaled reservoirs in Guangdong Province.