Ziyang County, Shaanxi Province, China is a world known selenium(Se)-enriched area, and a severe selenosis incident was reported in Naore Village during the 1990 s. This study investigated the geochemical characteristics of Se and its fractions in Se-enriched rocks from Ziyang. Se distribution is uneven, ranging from 0.23 to 57.00 μg/g(17.29±15.52 μg/g). Se content is higher in slate than chert, and even lower in carbonate rocks. Cd, As and V are enriched but Pb is depleted in Se-enriched strata. Se has different correlations both with TS(total sulfur)(R~2=0.59 for chert) and TC(total carbon)(R~2=0.77 for slate, R~2=0.87 for carbonate). Se has significant positive correlations with V(r=0.65), As(r=0.485), Cd(r=0.459) and Pb(r=0.405). The Se level correlates with mineral content, positively with pyrite, chlorite and illite, negatively with albite. Se associated with sulfide/selenide and elemental Se are the predominant fractions of total recovered Se, suggesting that a reducing environment and the formation of sulfides were significant to Se deposition during its geochemical cycle. Although low concentration of bio-available Se(average 5.62%±3.69%) may reduce the risk of Se poisoning in the target area, utilization of Se-rich rock as natural fertilizer should be restricted. Ziyang County, Shaanxi Province, China is a world known selenium (Se) -enriched area, and a severe selenosis incident was reported in Naore Village during the 1990 s. This study investigated the geochemical characteristics of Se and its fractions in Se-enriched rocks Se content is higher than slate than chert, and even lower in carbonate rocks. Cd, As and V are enriched but Pb Se has different correlations both with TS (total sulfur) (R ~ 2 = 0.59 for chert) and TC (total carbon) (R ~ 2 = 0.77 for slate, R ~ 2 = 0.87 for carbonate Se has significant positive correlations with V (r = 0.65), As (r = 0.485), Cd (r = 0.459) and Pb (r = 0.405). The Se level correlates with mineral content, positively with pyrite, chlorite and illite, negatively with albite. Se associated with sulfide / selenide and elemental Se are the predominant fractions of total recovered Se, suggesting that a reducing envir onment and the formation of sulfides were significant to Se deposition during its geochemical cycle. Although low concentration of bio-available Se (average 5.62% ± 3.69%) may reduce the risk of Se poisoning in the target area, utilization of Se-rich rock as natural fertilizer should be restricted.