The characteristics of fresh, freeze-dried, and hot-air-dried Brassica rapa L. were compared through analyses of the nutritional compositions, flavor characteristics, as assessed through gas chromatography-ion mobility spectrometry, and compound compositions, as evaluated by a principal component analysis. The water content of fresh B. rapa L. exceeded 85%, while the fat content was only 0.52 g/100 g DW and increased significantly after drying. The protein content was 9.82 g/100 g DW and decreased to 8.43 g/100g DW and 6.59 g/100g DW after freeze-drying and hot-air drying, respectively. The potassium content was highest (3 423.93 mg/100 g). Essential amino acids in fresh B. rapa L. accounted for 39.49%, which was similar to the protein pattern specified in the WHO/FAO standards. The essential amino acid ratio coefficient of hot-air-dried B. rapa L. was 80, which was close to the WHO/FAO recommended pattern protein. A total of 63 flavor compounds were identified by gas chromatography-ion mobility spectrometry. Aldehydes accounted for 43.28% in fresh B. rapa L. and decreased to 34.90% and 38.17% after freeze-drying and hot-air drying, respectively. The alcohol content in fresh B. rapa L. was 14.58% and increased by 6.35% and 3.09% after freezedrying and hot-air drying, respectively. The ester content in fresh B. rapa L. was 17.11% and increased to 25.02% and 18.74% after freeze-drying and hot-air drying, respectively. A cluster analysis revealed significant differences in flavor compounds between fresh and dried B. rapa L. Hot-air drying improved the nutritional value of amino acids in B. rapa L., while freeze-drying increased the proportion of high-quality flavor compounds. These findings provide a reference for the selection of drying methods for B. rapa L.