To explore the bacteriostatic substances contained in Rosemary, the bacteriostasis activity of rosmanol and carnosol isolated from ethyl acetate part of Rosemary extract, 95 % alcohol extract and chloroform extract of Rosemary were studied by disk diffusion test. The constituents were tested with Staphylococcus aureus, Microbacterium tuberculosis, Streptococcus hemolytius, Streptococcus pneumoniae, Escherichia coli, Shigella dysenteriae, Sh. sonnei and Pseudomonas aeruginosa. The results showed that rosmanol and carnosol had obvious bacteriostatic activity when the concentration was higher than 0.01 g/ml and 95 % alcohol extract and chloroform extract of Rosemary had certain bacteriostatic activity when the concentration was higher than 0.3 g/ml.