Abstract: In this experiment filter paper dispersion method was used to determine antibacterial effects about the ethanol extracts of four species Cupressaceae plants to three common bacterial diseases.The minimum inhibitory concentrations（MIC）of four species Cupressaceae plants were determined by the Liquid suspension culture method. The results showed that the ethanol extracts of four species Cupressaceae plants have certain bacteriostatic activity on the tested bacteria.Testing of bacteriostasis showed that strongest bacteriostasis was the plant extracts of Platycladus orientalis.The MIC of ethanol extracts of different plants were obviously different.