Abstract: Effects of weak magnetizing treatment on seed vigor in Maize were studied. The methods adopted were that the seeds with different vigor levels were treated for 6~10 days by 50HZ magnetic field. The results showed that the weak magnetizing treatment had significant and constant positive effects on seed vigor comparing with control. The ranges of the biggest increasing rate of the vigor index among the seeds of different vigor levels were 21.9%~122.9% for weight of fresh bud, 55.7%~102.5% for weight of fresh root, 29.7%~65.7% for weight of dry bud, 51.4%~93.0% for weight of dry root, and -10.87%~21% for seed conductance rate。The correlation between vigor index of root dry weight and yield were significant at 0.01 level of probability. The yield can be forecasted by calculation with equation Y=1.0922x+229.5562. The best magnetizing treatment time was 10 days for higher vigor seeds, 8~10 days for the middle and lower. The differences between strong and weak magnetizing treatment was also discussed in this paper.