In the experiment, Tenebno molitor L in different growing phrases are put in pulsing magnetic fields with different frequency. The result shows that pulsing magnetic fields affect the Tenebrio molitor L in adult phrase more than others. Due to the together action of the stable magnetic fields(50 - 120mT intensity) and the pulsing magnetic fields(50Hz frequency), the livability of the Tenebrio molitor L. in adult phrase decreased noticeably. In the respect of female Tenebrio molitor L, the egg - laying season shortened ten days and the number of eggs laid decreased notably.