Dry seeds of soybean “Hefeng 55” were irradiated by carbon ions at different doses. The characters including phenotype, plant height, branch number, yield trait and DNA fingerprint were investigated to explore the M1 mutagenic effects. The results showed that various phenotypes appeared after irradiation by carbon ions. The plant height and branch number of M1 generation were significantly inhabited by carbon ions. The pods, seeds and seed weight per plant as well as hundred-seed weight showed the same trend of decrease-increase-decrease along with the dose increment. However, these variations did not reach a significant level. Among these variations, a seed vessel mutant with the color turned from yellow to brown was selected from the M1 generation, and this trait could be inherited stably to M2 generation. RAPD technique was used to check the variations of genomic DNA fingerprint in control and brown seed vessel mutant. It was found that increasing bands or flawing bands were induced by carbon ion irradiation, and the genetic similarity coefficient was 0.9513. In conclusion, all the results show that carbon ion irradiation can induce the mutagenic effects on both the agronomic characters and genomic DNA of soybean.Cited