The mineralization of heterotrophic bacteria in low-wetland fish pond of the Huang-Huai-Hai plain was studied in 1993. The results were oheained as follows： (1) The respiration rate of heterotrophic bacteria were related with the content of organic matter and the water temperature of fish ponds. (2) The bacteria biomass of fish ponds showed a clearly seasonal change· but the distribution of heterotrophic bacteria biomass showed no difference in surface and bottom water. (3) The dymamic characteristics of heterotropic bacteria decomposition organic matter were as follows：At first,the transferee! organic matter was little,following the temperature and the bacteria biomass, the mineralization increased and reched the maximum in autumn, and then stopped with decaresein the temperature. (4) The intensities of mineralization organic matter varied in fish ponds to stock different fishs.