Abstract: In order to increase the number of viable bacteria of Bacillus coagulans Liu-g1 in fermentation liquid for producing protease, through single factor and orthogonal experiments, the authors studied the effects of different culture media and fermentation conditions on the number of Bacillus coagulans Liu-g1 viable bacteria. The results showed that: the optimal culture medium formula was soybean meal 1%, corn starch 1%, calcium carbonate 0.2%. With the optimal formula of culture medium, under the fermentation temperature of 45℃, inoculation quantity of 2%, the volume of liquid of 50 mL, pH 7.5, fermentation time of 48 h, the speed of fermentation of 180 r/min, the highest number of viable bacteria of fermentation agent could be obtained, which was 9.53×109 CFU/mL. Under this condition, the number of viable bacteria of fermentation agent was 28.88 times as much as that before optimization.