Changes of microbial biomass and functional diversity in red soil were determined under different land use types. Results showed that land use type significantly influenced the various aspects of soil quality. Soil microbial biomass was higher in paddy soil, but medium in grassland and forestry, while in arid-land soil the contents of microbial biomass C and N were minimum (4.3% and 13.7% of those in paddy soil respectively). Microbial functional diversity was higher in paddy soil, while bacterial diversity was lower in arid-land, forestry and grassland, fungal functional diversity was lowest in arid-land soil. Microbial biomass and functional diversity, as an early and sensitive indicator, could be used to evaluate the effect of land use type or management on soil quality.