The dominant genera of heterotrophic bacteria and filamentious fungi in soils under different types of forest on Wuyi Mountain were studied in this paper. The results showed that the soils had dominant specific genera and relative density of heterotrophic bacteria and filamentous fungi under different types of forest. It was also true even in the different layers of the same soil profile. Generally speaking, in the fertile soils, the dominant genera were large in the amount, with a higher relative density.