Bitterness and astringency of the summer-autumn tea affect tea quality. The effect of shading on chemical compositions related to bitterness and astringency in tea leaves at different growing seasons was investigated. The results showed that the amino acids increased, the tea polyphenols and the ratio of polyphenols decreased, which optimizing the amino acid and catechin components; moreover, total chlorophyll content increased, which indicated that shading could effectively improve the tea quality. The degree of shading effect on the tea quality was: summer > autumn > spring. The double-layer cover of a black net gave a better result than the mono- layer cover.