The effects of different spraying periods and different concentrations of selenium on photosynthetic characteristics，grain selenium accumulation，quality and yield of “jin tartary buckwheat 5” were studied by foliar spraying.The results showed that low concentration of selenium significantly promoted plant growth，while high concentration of selenium inhibited plant growth.When selenium concentration was 1 mg·L-1 or less，all the indexes of the plants，except the total seeds flavonoids，were significantly improved with the increased concentration of selenium，and the concentration of 0.5 mg·L-1 was the best.Compared with T0，the SPAD of T0.5 increased by 1.9%～2.2%，the net photosynthetic rate increased by 3.2%～5.0%，dry matter accumulation increased by 1.2%～2.0%，the selenium content in grains increased by 1.5～17.7 times，protein content increased by 1.1%～1.6%，the fat content increased by 2.5%～2.6%，the content of total flavonoids decreased by 2.2%～4.5%，grain 1000-grain weight increased by 3.0%～3.7%，yield increased by 9.9%～12.4%.In a word，selenium by foliar spraying could significantly improve the photosynthetic rate，grain selenium content，grain quality and yield of “jin tartary buckwheat 5”，but it was not conducive to the accumulation of total flavonoids.Selenium of 0.5 mg·L-1 by foliar spraying in the bud stage was the best.