Abstract: Sodiumm selenite, as a nutrient source of selenium was used to culture spirulina and the influence of gradient concentration of sodium selenite on the growth of Spirulina platensis and selenium enrichment content had been researched. Moreover,the selenized component of selenium-enriched spirulina was studied with the tracer technique of 75Se labeling Na2SeO3. The results showed that the growth of spirulina was inhibited as the selenium concentration beyond 360 g/mL. Otherwise, trend of low selenium concentration (46 g/mL) promoting the growth of spirulina was also showed.The highest selenium content of spirulina reached 659. 9ng/mg on an average. while the selenium concentration in medium was 184 g/mL. In the selsnium-enriched spirulina,the content of organic selenium which were connected on the macromolecules amounted over 70%. the main selenized protein reached over 50%, seleno-methionine and selenocysteine accounted for 40% and 20% of selenized protein respectively.