Abstract: Objective To study the effect of static magnetic fields and low-frequency time-varying magnetic field on the micronucleus in PCE of the mouse bone marrow and blood analysis.Methods The static magnetic fields(40mT、50mT、60mT)and low-frequency time-varying magnetic field(10mT、16mT)were used,in a frequency of twice every day for two hours each time.A fter 15 days the micronuclei rate of mouse bone marrow and blood cell were deter mined.Results There were significant differences between experiment group and control group(P<0.05),but the amount of erythrocyte did not significantly change.The amount of leukocyte of low-frequency time-varying magnetic field group was significantly decreased.Conclusions The experiment demonstrated that 40mT、50mT static magnetic fields and 10mT、16mT low-frequency time-varying magnetic field probably induced biological cell to change.