Abstract: Species and population of microorganisms in the water body of Jinji and Shang lakes had been investigated from June 1998 to October 1999. The results show that the amount of heterotrophic bacteria is 17000～260000/mL in the Jinji Lake, being higher than that in the Shang Lake(500～80000/mL),and its highest density appeares in October;densities of actinomyces and molds are lower, 0～19/mL, 0～7/mL in the Jinji Lake and 1～25/mL,0～37/mL in the Shang Lake, respectively; amount of coliform is higher in the Jinji Lake than in the Shang Lake, 350～16000/L and 20～250/L, respectively, suggesting that the enrollment of waste water and fertilizer application for fishing in the Jinji Lake have significant effect on the amount of coliform; 8 genera in the Jinji Lake and 9 genera in the Shang Lake have been found and the dominant groups are Vibrion, Aeromonas, Bacillus and Acinetobacter, Pseudomonas, Bacillus, respectively.