This study investigated the effects of fermentation on the flavor quality of chlorotic tea cultivars (Camellia sinensis) with floral and fruity characteristics， focusing on chemometric analysis of Mingguan black tea processed under controlled temperature (25 ℃)， relative humidity (90%)， and ventilation conditions across four fermentation durations (0 to 3.5 h). The results revealed that fermentation duration had significant and complex effects on both the quality characteristics and chemical composition of Mingguan flora-fruity black tea. As the fermentation process progressed， the leaf appearance transitioned from yellow to brown， and the liquor and infused leaf displayed increasingly bright red hues. Notably， both the preliminary fermentation triggered by rolling and moderate fermentation were more favorable for developing superior flavor profiles. Chemically， the major quality constituents and metabolite profiles of the tea also demonstrated systematic changes throughout fermentation. Specifically， the total tea polyphenol content decreased from 6.26% to 3.61%， and soluble sugars declined from 4.81% to 3.74%， whereas the contents of free amino acids and caffeine showed no significant changes. Non-volatile and volatile metabolic profiles exhibited pronounced differences across different fermentation durations. Most non-volatile metabolites significantly declined over time， whereas most volatile metabolites increased after 0.5 h of fermentation and remained abundant. The distinctive flavor profile of Mingguan flora-fruity black tea was closely associated with the inherent characteristics of its raw materials and the differential regulatory effects of fermentation duration on the key metabolites. These comprised 8 sweet-tasting non-volatile metabolites， such as 2′-deoxyadenosine-5′-monophosphate， adenosine-2′-phosphate， and n-octyl-β-D-glucopyranoside； 14 bitter-tasting non-volatile metabolites， including adenosine， nicotinamide， and kaempferol-3-O-(6″-malonyl)-glucoside； and 19 volatile metabolites that contribute to its sweet， floral， and fruity aromas， such as α-cedrene， 1-decanol， and butyl hexanoate. The findings offered valuable insights for the development of floral- and fruity-aroma black tea products derived from chlorotic cultivars， and for the targeted modulation of their flavor quality.