Abstract: Taking the tea plant variety Shancha 1 as the experimental material and spraying clear water as the control (CK), five treatments of M₁~M₅ (20, 40, 60, 80 and 100 μmol/L sodium selenite) were set up to explore the effects of sodium selenite concentrations and harvesting time on selenium content and quality of tea leaves. The results showed that the selenium content decreased with the increase of picking time, while the selenium content in tea increased with the increase of sodium selenite concentration during the same picking period. The optimal concentration of sodium selenite for selenium-enriched cultivation of Shancha 1 was M₃ (60 μmol/L sodium selenite). Compared with CK, the tea theanine and tea polyphenol contents of the tea leaves in different treatments were decreased by 3.14%~34.08% and 4.35%~9.68%, respectively. The correlation analysis indicated that the selenium content of tea leaves was highly significantly positively correlated with the polyphenol content (r=0.830). Tea polyphenol content was significantly positively correlated with the polyphenol content (r=0.432), but was not significantly correlated with the phenol-to-amino acid ratio of tea leaves. However, the theanine content was highly significantly negatively correlated with the phenol-to-amino acid ratio of tea leaves (r=-0.901), which indicated that spraying selenium fertilizer on Shancha 1 led to a decrease in theanine content, resulting in an increase in the phenol-to-amino acid ratio of the tea, and was more conducive to the development of black tea. The research results can provide an important reference for the cultivation of Ankang selenium-enriched tea and the comprehensive utilization of summer and autumn tea.