It has good antibacterial effect on Streptococcus species such as hemolytic streptococcus, Streptococcus pneumoniae and Staphylococcus that do not produce penicillinase. It has moderate antibacterial effect on enterococcus. Neisseria gonorrhoeae, Neisseria meningitidis, Corynebacterium diphtheria, Bacillus anthracis, Actinomyces bovis, Streptobacillus moniliformis, Listeria, Leptospira and Treponema pallidum are sensitive to this product. This product also has certain antibacterial activity against Haemophilus influenzae and Bordetella pertussis, while other gram-negative aerobic or facultative anaerobic bacteria have poor sensitivity to this product. This product has good antibacterial effect on Clostridium, anaerobic bacteria of digestive streptococcus and Bacteroides melanogenes, but poor antibacterial effect on Bacteroides fragilis. Penicillin plays a bactericidal role by inhibiting the synthesis of bacterial cell wall.