Synchrotron radiation X-ray absorption near edge structure was employed to study the arsenic (As) speciation in 13 Pteris vittata L.populations collected from 7 provinces,cities,and autonomous regions in China.As in roots of P.vittata was mainly combined with oxygen (O),with a small amount of As combined with glutathione (GSH).Populations from Hunan and Guangxi provinces showed higher percentages of As-GSH in soots.As in roots of P.vittata was predominated with As(Ⅴ),with the percentage of As(Ⅴ) to the total As being 59.6±0.6%~83.8±3.8%.The As(Ⅴ) percentage was in the order of HN5HN3>HN1>TW>CQ>AH>FJ>HN5>HN2>GX2>GX3>HN4>GX1,within the range of 2.4%~12.9%.Different from that in roots,As in shoots was predominated with As(Ⅲ),with no As(Ⅴ) detected.The disclosure of As speciation in the roots and shoots of P.vittata contributes to the future research on As accumulation mechanism.