A bacterium strain, GY04, was isolated from sand soil of a maize field in suburb of Guiyang. The analysis of DNA sequence suggests that the strain of GY04 is Agrobacterium radiobacter. With the principle of the uniform design, the fermentation conditions of the strain GY04 are optimized. Analyzing by SPSS(V10.0), the optimal fermentation process is determined. They are beef extract 2.000g/L, glycol 2.775 g/L, calcium carbonate 2.000g/L, the initial pH7.000, the inoculum amount 7.000%. On these conditions, the production of the saccharide can be achieved the most, about (2.683±0.600) g/L. The results also show that bacterium A. radiobacter possess good waterretention ability as a microbial waterretaining agent.