We took fresh cow dungs as aerobic compost,and took samples at intervals of 3 d, which were cultivated in such culture mediums as beef cream-peptone, Gause1, PDA and bean routs. By dilution, the fermenting microorganism separation, cultivation, counting and verification were carried out. The results showed that the dominant genera microflora in the fresh cow dungs were bacteria. During the course of fermentation, the number of bacteria were 104~105 times larger than that of actinomycetes and molds. And the bacteria were the dominant microbe in this course. In heating stage, the mesophilic bacterium was the main flora, and thermoactinomyces and thermophile were the main flora in high temperature stage. Mold was the dominant bacterium group in low temperature stage. Further verification indicates that bacillus and cellulomonas in bacterium flora, micropolyspora, micromonospora and thermoactinomyces in ray fungi, trichoderma, koji mold and blue mould in mildew were dominant flora during the course of fermentation. Yeast did not participate in the fermentation process.