The finished black tea with strong grass smell and bitter taste was used as material, the orthogonal test (L9 (34)) was conducted with factors of temperature, moisture and time by using heat–moisture post–treatment and comprehensive sensory score and physicochemical data were referenced, to study the optimum technological parameter of heat–moisture post–treatment on improving the flavor quality of black tea and make comprehensive evaluation. The results showed that: The optimal technological parameters were temperature 65 ℃, water 10% and time 7 h; Compared with the original sample, the score of processed sample on liquor colour, aroma and taste were significantly increased (P<0.05); its polyphenols and catechins (especially catechins ester) contents were significantly decreased but thearubigin content was significantly increased (P<0.05); In amino acids composition, the sweet and umami taste amino acids contents were increased while bitter amino acids were decreased; In aroma components, aroma with grassy and unpleasant smell including trans–2–hexyl alcohol, hexyl alcohol, caproic acid and so on were decreased, while aroma with sweet, floral and fruity smell including alpha cedar alcohol, 2–methyl butyl aldehyde, 3–methyl butyl aldehyde, alpha terpinene, limonene and 2–ethyl furan were increased obviously.