The high titer rabies virus (RV) bulk was prepared by optimizing the culture condition of aG strain through improving the buffer system of maintenance medium.Conventional virus maintenance medium was supplemented with buffer salt and sodium bicarbonate.RV aG strain was cultured under the same conditions by using conventional and modified maintenance media resp. and harvested for 2 times.The harvested virus liquid was pooled and purified by ultrafiltration with 300 KD membrane and Sepharose 4FF chromatog., and the prepared virus bulk was determined for antigen content by ELISA, for titer, potency, host DNA and residual host cell protein according to the requirements in Chinese Pharmacopoeia (Volume III, 2010 edition), and for pH value by portable pH meter.The antigen content, virus titer and potency of bulk cultured in modified maintenance medium were higher than those in conventional medium.The host protein and host cell DNA contents in bulks cultured by both the maintenance media met the requirements in Chinese Pharmacopoeia (Volume III, 2010 edition).However, the modified maintenance medium was superior to conventional maintenance medium in buffer ability and control of pH value during virus culture.As compared with that in conventional maintenance medium, the titer of virus bulk prepared by culture of RV in modified maintenance medium was high.