To investigate the radiation protection of WSC-DTPA nanoparticles, N-acylation reaction and ion crossing-linking method were used to prepare nanoparticles in different remaining free amino groups. MTT assay was performed to evaluate their effects on the viability of the cells after γ-rays irradiation, while the capability of FITC-WSC-DTPA nanoparticles probe penetrating through cellular membrane was observed by Live Cell Station. The results show that WSC-DTPA polymers were successfully synthesized, in which the content free amino group is 92.7%, 74.3%, 1.59%, respectively. Compared with γ-rays alone group, it was shown that WSC, WSC nanoparticles and WSC-DTPA nanoparticles with the concentration more than 6.25 μg/mL and the free amino group content around 92.7% have good efficacy in radiation protection to BRL cells from damage induced by 6 Gy 60Co γ-rays by the higher survival rate, while WSC-DTPA nanoparticles with 1.59% free amino group content do not have radiation protection to BRL cells. The WSC nanoparticles and WSC-DTPA nanoparticles can penetrate into cellular within 2 h, while WSC-DTPA polymers could not pass through the membrane.Cited