In order to explore the sensory quality of cigar tobacco leaves and its key differential components under different nitrogen application rates, and to analyze the material basis of the flavor characteristics of cigar tobacco leaves in Hunan. The cigar variety CX81 was used as the test material, and four nitrogen application treatments were set up : N0 ( 0 kg/hm2, CK ), N1 ( 180 kg/hm2 ), N2 ( 210 kg/hm2 ), N3 ( 240 kg/hm2 ). The sensory quality of fermented cigar leaves was evaluated and the main chemical components were analyzed. Orthogonal partial least squares discriminant analysis (OPLS-DA) was used to screen the key difference indicators under different nitrogen application rates, and the relationship between them and sensory quality was explored. (1) The results showed that the increase of nitrogen application rate could improve the smoke intensity, alcohol content, pollen aroma and glutinous rice aroma of cigars.(2) With the increase of nitrogen application rate, the total nitrogen, nicotine and browning reaction products of cigar tobacco leaves increased significantly, the total amount of phenylalanine degradation products, carotenoid degradation products, neophytadiene and neutral aroma substances increased first and then decreased, and the total sugar, reducing sugar and cembranoid degradation products decreased gradually. (3) The main chemical components were screened, and 21 key differential components were screened out. Among them, 7 key differential components were significantly positively correlated with sensory quality, and 1 was significantly negatively correlated. (4) The increase of nitrogen application rate mainly increased the sweetness and woody aroma of cigars by increasing the total amount of neutral aroma substances (except neophytadiene), increased the content of benzaldehyde, furfural, 3,4-dimethyl-2,5-furandione and browning reaction products, increased the total nitrogen and nicotine, reduced the mass fraction of reducing sugar, improved the smoke intensity and smoke alcohol and sense, and enriched the aroma of pollen and glutinous rice.