Wheat (Triticum aestivum L) seeds were irradiated with different doses of 12C6+ ion beams. Several biological endpoints including seeds germination rate, seedling root length and plant height, mitotic activities and survival rate were investigated. The results showed that in all dose range, most irradiated seeds were able to germinate normally. Low doses radiation (10–20 Gy) had a stimulation effect on seedling growth, while high doses radiation played an inhibition role. Especially root growth was strongly related to mitotic index. MI increased in low doses and decreased in high doses, and the mitotic cells were arrested in metaphase and anaphase. The survival curve showed that the “parabola” trend and the median lethal dose (LD50) was 55 Gy.Cited