Huguang microbial additive is comprised of strains of photosynthetic bacteria, including Rhodopseudomonas and Rhodospirillum. The essential technical parameters in batch culture, such as media, illumination, temperature, pH, aeration and inoculation ratio etc. were studied. In general, after incubation for 3-5 days under appropriate conditions, the culture became deep red in colour and the cell number increased to about 10-9/ml. When preserved at room temperature for 6 months, the microbial additive remained still effective; and when incubated at 40 degree C and in dark condition for 15 days most cell survive in culture. A simple method for quality assay of the microbial additive is presented.