Abstract: The Escherichia coli and Staphylococcus aureus under different growth phases and different temperatures and pH values were inactivated by pulsed magnetic field. Logarithmic-phase microorganisms were more sensitive than stationary- and lag-phase microorganisms to the pulsed magnetic field. Inactivation effects of two microorganisms begin to be poorer at later period of logarithmic-phase and this rebound trend prolonged to lag-phase and tended gradually to smoothness. The rate of inactivation increaseed with the increase of temperature. The temperature was much less than the one of microorganism death caused by heating. The more pH value tended to neuter, the poorer effect of inactivation was; when pH value was less than 5, effect of inactivation was better.