Abstract: Environmental factors, photosynthesis and evaporation characteristics, and tea ingredients were studied at a selected tea field with 80%, 61% and 37% shadings in the summer and autumn. Results show that shading operation remarkably reduces air temperature, leaf surface temperature, ground temperature and soil temperature, and increases soil water contents and air humidity. Shading effects on tea garden environment are enhanced with increase in shading degree. In comparison with unshaded tea garden, net photosynthetic rates of tea under 80%, 61%, 37% shadings increase by 365%, 283%, 68% respectively; chlorophyll-a contents in the tea leaves increase by 57.5%， 29.3% and 15.9%， and total chlorophyll contents increase by 52.2%, 29.2% and 14.3% respectively; amino-acid (AA) contents increase by 68.6%, 33.5% and 2.16% respectively; and tea polyphenol (TP) contents drop by 15.3%, 12.5% and 5.4% respectively. TP/AA ratio in processed tea from two-leaf and one-bud-shoot under 80% shading meets high-grade green-tea standards, and that at 61% and 37% shadings reaches fine-grade green-tea standards; much better than those of unshaded tea gardens.