This study examined the effects of various treatments on the root length,plant height,biomass,chlorophyll content,reactive oxygen species,and CAT enzyme activity of rapeseed when selenium source and nano-selenium with different salt concentrations were used as test objects..The results indicate that the application of selenium has a promoting effect on the phys-iological growth of rapeseed under high salt stress,significantly enhancing the root length,plant height,and biomass of rapeseed.The application of nano-selenium has a more pronounced promoting effect on the physiological growth of rapeseed.The con-tent of reactive oxygen species in the selenium-containing group is significantly lower than that in the selenium-free group,in-dicating that selenium has a role in scavenging reactive oxygen species.The content of CAT enzyme in the selenium-containing group is higher than that in the selenium-free group,indicating that selenium can enhance the activity of CAT enzyme and im-prove the stress resistance of rapeseed.This study can provide a theoretical basis and technical support for crop stress resistance.