Abstract: The changes of culturable microorganisms in upland and flooded paddy red soils following rice straw and selective inhibitors amendment was studied during a 45 day incubation period at 25℃. The results showed that, compared with the treatment of control (CK), the amount of culturable bacteria and fungi in the soil amended with rice straw were increased by 271.4% ~ 518.8% and 2900% ~ 3608% respectively, during the incubation period of upland soil, the addition of fungicide actidione increased the amount of culturable bacteria by 34.1% ~ 81.4% compared to the rice straw. In the treatments of the addition of bactericides tetracycline and streptomycin sulphate, the amount of culturable bacteria decreased by 14.3% ~ 43.48% compared to the rice straw, however, the amount of culturable fungi increased by17.1% ~ 37.6%. During the incubation period of the flooded paddy soil, the amount of culturable bacteria increased by 115.3% ~ 362.2% in the treatment of rice straw application, whereas the amount of culturable fungi decreased by 5.8% ~ 27.8%, compared to the control (without rice straw amendment). The effects of the fungicide actidione on culturable bacteria and fungi were similar to rice straw amendment correspondingly, the amount of culturable bacteria decreased by 39.0% ~ 76.2% in the treatment of the bactericides tetracycline and streptomycin sulphate combined with straw compared to the treatment with rice straw only. In addition, under the condition of the red earth soils amended with rice straw, the ratios of bacteria to fungi content decreased dramatically in upland soil, but increased quickly in flooded paddy soil amended with rice straw. The results illustrated that the application of rice straw had significant effects on the growth of bacteria and fungi in upland soil, and fungi possibly played a key role in the straw decomposition and transformation, but in paddy soil the role may be played by the bacteria. Furthermore, our study suggest that soil microbial community changes were influenced greatly by soil moisture content in red earth soil following amendment with rice straw.