Lowtempreature plasma （LTP） treatment of seed before sowing is the largest application of mordern physical method in agricultural production. As a conductor, plasma is known as the four states of matter, belongs to the areas of physical discipline. Lowtemperature plasma stimulation plays an important role in optimizing crops in terms of activation of endogenous substances in the seeds rejuvenation, promotion of plant grown, protection against disease, and the maximization of yield. Plasma seed processing technology is the use of high energy aggregation on treating crop seeds within 20 s. The LTP plasma stimulation could improve seed germination and seedling growth. This technology was applied practically and works well now. In this paper, the effects of different intensities of LTP on Alfalfa seeds were investigated on the fourth and twentieth days after treated. The vigor, germination rate, germination index, wintering ability, returning green stage, plant height, tillers and pod growth were compared for treated and untreated seeds. The result shows that LTP could improve alfalfa seeds germination and seedling growth，and advance the reviving stage. There is a great value of using and spreading on production.