Abstract: In this paper, we study bacteria and fungi in the spirulina culture ponds in Chenghai factory. The results showed that the enumeration of total bacteria is 104—107/mL, the enumeration curve showed certain regularity with the culture time. The death of spirulina had major relation to the resistance of spirulina species and certain relation to the total bacteria enumeration. The dominant bacteria and fungi were Neisseria, Staphylococcus, Micrococcus, Enterobacteriaceae, Paecilomyces, Aspergillus and Ozonium. A few strains obviously inhibited or promoted the growth of spirulina chiefly through their metabolite.