The healthy duckings were selected as laboratory animals, and the models of selenium deficiency and selenium poisoning were reconstructed, by the newest method of modern pharmacology and toxicology this paper studied for the first time and comprehensively: (1) The pharmacokinetics and toxicokinetics of sodium selenite in ducklings with different selenium level (normal selenium level, deficiency selenium level, poisoning selenium level) to guide reasonable employment of drug of veterinary clinic; (2) The toxicology of sodium selenite in duckings to deeply reveal molecular mechanism of selenium poisoning. The results were as follows:1.The characteristics of blood-phamacokinetics:Deficiency selenium level: Conforming to the first order absorption and two compartment open model, the theoretical equation was:C=-0.0439e-26925'+0.1085e-00053t-0.0646e-?"74tThe primary kinetic parameters: the half-life absorption (T^Ka) was 5.9026hrs,the time of reaching maximum concentration (Tmax) was 23.03 hrs,the half-life of elimination (T1/2b) was 131.13hrs,the area under the curve (AUC) was 19.93 Mg/1 旽rs, and the volume of distribution (Vd) was 7.60389 L/kg.Normal selenium level: Conforming to the first order absorption and two compartment open model, the theoretical equation was:C=0.1147e-0.1284t+0.0080-0.00183t-0.1227e-(1-8077tThe primary kinetic parameters: the half-life absorption (T^^a) was 0.8580hrs,the time of reaching maximum concentration (Tmax) was 2.79hrs,the half-life of elimination (Tiae) was 37.95hrs,the area under the curve (AUC) was 17.02 Mg/1 ?Hrs, and the volume of distribution (Vd) was27.8465L/kg.Poisoning selenium level: Conforming to the first order absorption and two compartment open model, the theoretical equation was:C=0.1151e-0.1601t+0.0508-0.0050t-0.1659e-01.11.5tThe primary kinetic parameters: the half-life absorption (T|/2Ka) was 0.6240hrs,the time of reaching maximum concentration (Tmax) was 2.39hrs,the half-life of elimination (TIQS) was!38.24nrs,the area under the curve (AUC) was 10.694 Mg/1 ?Hrs, and the volume of distribution (Vd) was22.3977L/kg. 2.The characteristics of tissue kinetics:Deficiency selenium level: liver, kidney, spleen, pancreas and gizzard conformed the two compartment open model with the first order absorption, heart conformed the onecompartment open model with the first order absorption, muscle conformed the one compartment open model and first order absorption with a lagtime. The absorption of selenium in tissue liver were quickest, heart, gizzard, pancreas, kidney and spleen were in order of becoming slower, muscle was the slowest and with a lagtime; The elimination of selenium in tissue was all slow, muscle were the quickest, heart, liver, spleen, kidney, pancreas and gizzard were in order of becoming slower.Normal selenium level: heart, liver, kidney, spleen, pancreas and gizzard conformed the two compartment open model with first order absorption, muscle conformed the one compartment open model and first order absorption with a lagtime. The absorption of selenium in tissue liver were quickest, kidney, pancreas, heart, spleen and gizzard were in order of becoming slower, muscle was the slowest and with a lagtime (1.21hrs) , Tmax was 20.55hrs;The elimination of selenium in tissue was all slow, muscle were the quickest, liver, pancreas, kidney, spleen, jiwei and heart were in order of becoming slower.Poisoning selenium level: liver, kidney, spleen and gizzard conformed the two compartment open model with first order absorption, pancreas conformed the two compartment open model and first order absorption with a lagtime , muscle conformed the one compartment open model and first order absorption with a lagtime, heart conformed the one compartment open model with first order absorption. The absorption of selenium in tissue liver were quickest, heart, kidney, gizzard, pancreas and spleen were in order of becoming slower, muscle was the slowest and with a lagtime; The elimination of selenium in tissue was slow compared w