In order to provide effective medical triage for a large number of individuals exposed to radiation in event along with the dose reconstruction, 30 healthy fingernails were collected. After irradiation, the samples was treated with distilled water for 10 min to eliminate the mechanical induced signal (MIS) when the samples of fingernails were stressed by cut for collection. The samples were irradiated by Cs-137 with different absorbed doses and the determination of radicals of samples was performed by EPR immediately after irradiation. The experimental results show that the EPR signals of samples are linear with the absorbed doses and the slope of the equation is followed normal distribution (p<0.5), which suggest that dose reconstruction by use of fingernail after any nuclear accidents may be feasible if the absorbed doses are more than 3 Gy.Cited