To understand the soil microbial community structures of different locations and altitudes, as well as the fluctuation of microbial populations foward seasonal change, this study investigated the biodiversity of soil microbiota of eight sampling sites along the Lao-Nong River basin during 4/11/2003~3/21/2004. The results showed that the soil properties were different among these sampling sites. The soil temperatures were ranging in between 24~32¢J, except Tianchr, the highest altitude sampling site (7~19¢J) ; pH values were 4.00 (Tianchr) ~8.20 (Tauyuan) ; moisture contents were 2.31% (Liouguei) ~70.23% (Tianchr) ; total organic carbon contents were 0.38% (Linkou) ~36.21% (Tianchr) ; total organic nitrogen contents were 0.067% (Tauyuan) ~0.672% (Tianchr); the C/N ratio were 7.0~25.0, except Tianchr (42 in average) . In microbial community structures analysis, bacteria were the most abundant organisms among all soil samples (106~108 CFU per gram of soil) . The amount of other microbes were as follow: nitrogen-fixing microbes 105~107 CFU, actinomycetes 104~107 CFU, fungi 104~106 CFU, cellulolytic microbes 104~106 CFU, and the least one was phosphate- solubilizing microbes 103~105 CFU. For molecular biological microbiota analysis, the bead-beating DNA extraction method resulted the richest bacterial 16S rDNA DGGE profile. The16S rDNA DGGE profiles of various samples taken from different seasons showed somewhat seasonal variations that might relate to the specific climates of Taiwan, such as the plum rains and typhoons. Moreover, we also successfully cultured and preserved many microbes with specific biological functions. These microorganisms will provide a useful resource for further research and development in the biotechnology industries.