Abstract: To investigate the effects of foliar spraying of sugar ester（SE）, brassinosteroid（BR）, and ammonium molybdate（AM） on the yield and quality of upper flue-cured tobacco leaves of Yunyan 87, a field experiment was conducted with six treatments: CK（water spray）, T₁（SE）, T₂（BR）, T₃（AM）, T₄（SE + BR）, and T₅（SE + AM）. The physical properties, chemical composition, neutral aroma substances, sensory quality, and economic traits were measured, and principal component analysis（PCA） was used to comprehensively evaluate the effects of each treatment. The results showed that T₄ and T₅ significantly promoted internode elongation of tobacco plants and improved the physical properties and conventional chemical composition of B2F leaves. The total content of neutral aroma substances in T₄ and T₅ increased by 49.22% and 33.58%, respectively, compared with CK. The yield and output value of all treatments were significantly higher than those of CK, with T₅ exhibiting the highest values. The proportion of high-grade leaves, yield, and output value in T₅ increased by 13.63 percentage points, 25.94%, and 23.40%, respectively, compared with CK. Comprehensive evaluation indicated that T₅ achieved the best overall effect, with a comprehensive score 2.80 times higher than that of CK. T₄ showed a comprehensive score 2.64 times higher than that of CK. In conclusion, foliar application of SE combined with AM can effectively improve the overall quality of upper tobacco leaves and is suitable for extension in the Xiajiang tobacco-growing area. Meanwhile, foliar application of SE combined with BR can significantly enhance the intrinsic quality of tobacco leaves, particularly in terms of neutral aroma substance content and sensory quality, and is therefore recommended for tobacco-growing areas where intrinsic quality improvement is needed.