Abstract: In this research, Perilla frutescens seeds were treated with different magnetic field intensity for 0h、1h、2h、3h、4h and 5h respectively. The results showed that the seed germination rate gradually increased as the treatment time prolonged for 20.9mT, the highest germination reached 89% for 3h with magnetic field treatment; When seeds were treated with magnetic field for 42.5mT, the seed germination rate reached more than 90% in all treatment time, far higher than that of the control; this result indicated that it was benefit for perilla frutescens seed germination with magnetic field treatment for 42.5mT; with the magnetic field for 42.5mT, plant height, root length and root number reached maximum at 3h; the POD and nitrate reductase activity increased obviously after the magnetic treatment for 3h; all these results demonstrated that the optional dealing-time was 3h for perilla frutescens seeds with magnetic field for 42.5mT strength.