The 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH·), hydroxyl free radical (OH·), 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radical (ABTS⁺·) and superoxide radical (O^-₂·) scavenging ability were selected as the four indicators to evaluate the in vitro antioxidant properties of different selenium-containing substances, and compared with selenium-enriched yeast (SY) and non-selenium-enriched peptides and inorganic selenium mixture (SPIS).The results showed that SPI had the strongest ability to scavenge four kinds of free radicals, and its DPPH·, OH·, ABTS⁺· and O^-₂· scavenging rates were 87.5%, 50.3%, 99.7% and 45.7%. The weakest sample was IS, and its radicals scavenging rates was no more than 14%. By comparing the scavenging rates and semi-inhibitory concentration (IC₅₀) of four radicals of SPR, SPI, CE, SY, IS and SPIS, it was found that the ability to scavenge free radicals of organic selenium was stronger than inorganic selenium.