Taking Kashi gray jujube as the object，foliar spraying of selenium fertilizer in the flowering period and fruit setting period of jujube trees was conducted to study the effects of foliar spraying of selenium fertilizer on the content of selenium in jujube fruit under different periods，different selenium fertilizers and different concentrations of treatments. The changes process of selenium content during the development period of jujube fruit were analyzed，the suitable concentration and period of selenium fertilizer spraying were screened out. The results showed that the foliar spraying of selenium fertilizer significantly increased the selenium content in the fruit of jujube，and achieved the effect of selenium enrichment，and the selenium content increased with the increase of selenium application，reached its maximum value during the fruit expansion period，and then decreases slightly during the ripening period. In the late ripening stage of jujube fruit，the selenium content of the fruit treated with inorganic selenium fertilizer in the fruit setting stage was higher than that in the flowering stage. From the perspective of the absorption of selenium by the fruit，it showed that no matter whether the jujube was sprayed with inorganic selenium fertilizer or organic selenium，the key period for applying selenium fertilizer was the fruit setting period. In the late stage of jujube fruit ripening，the treatment of spraying inorganic selenium fertilizer 40 mg/L in the fruit setting period significantly increased the selenium content of the fruit，the selenium content reached 0.2698 mg/kg；the treatment of spraying organic selenium fertilizer 32 mg/L during the fruit setting period increased the selenium content of the fruit significantly，the selenium content reached 0.2226 mg/kg，and the selenium contents of the fruit under the two selenium fertilizer treatments both reached the national standard for selenium-enriched agricultural products. To sum up，spraying 40 mg/L inorganic selenium fertilizer or 32 mg/L organic selenium fertilizer during the fruit setting period is most suitable for local production needs.