Abstract:In order to study the effect of the basic physicochemical properties on microbial diversity, three different flooded paddy in the Southwestern China were selected. Drying method, potential metric method, static indoor culture method, diluted coating plate method and chloroform fumigation method were used to test the soil physicochemical and biological indexes. The results indicated that:(1) The water content of each sample area gradually reduces along the vertical depth. The pH value was between 6.3~7.1 from slightly acidic to neutral. Ammonium nitrogen (NH4+-N) content ranged as Hechuan flooded paddy field>Shapingba flooded paddy field>Beibei purple soil base, and the surface (0-10 cm)>subsurface stratum (10-20 cm)>bottom (20-40 cm), while the overall content was 36.97~52.02 mg/kg. The difference of nitrate nitrogen (NO3--N) in three kinds of flooded paddy fields was not significant (2.13~2.61 mg/kg). (2) The content of microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) in Beibei purple soil base was the most, followed by Hechuan flooded paddy field, and Shapingba flooded paddy field, while the content of MBC and MBN decreased with the increase of soil depth. (3) The microbial abundance showed the trend of bacteria>actinomycetes>fungi, and decreased with the increase of soil depth. The Pearson relationship analysis showed that the abundance of soil bacteria, actinomycetes and fungi had a significant negative relationship with each other (p<0.01). The microbial abundance showed the trend as Hechuan flooded paddy field>Shapingba flooded paddy field>Beibei purple soil base.