Abstract: To investigate the effect of rosemary extract deodorizing solution on the deodorization of mackerel, the deodorization process was optimized using one-way and response surface tests, and the volatile components of mackerel before and after deodorization were identified by gas chromatography ion mobility spectroscopy (GC-IMS). The results indicated that the volatile flavors of mackerel were significantly different before and after deodorization. The lowest TBA and sensory fishy flavor values of 0.881 mg MDA/kg and 1.34 score, respectively, were obtained at a concentration of 0.16% in rosemary extract deodorizing solution, a mass-liquid ratio of 1:3.3 (g/mL) and an immersion time of 41 min. A total of 45 volatiles were detected by GC-IMS, with the highest relative content of aldehydes before deodorization. After deodorization treatment, the relative content of aldehydes was significantly reduced by 30.73%, and the relative content of ketones and esters was significantly increased (P<0.05), by 0.87 and 2.11 fold, respectively. An orthogonal partial least squares discriminant analysis (OPLS-DA) was utilized to develop a model with reliable stability. Based on the variable importance in projection (VIP), the key flavor substances before deodorization (VIP>1) were identified as hexanal (M), hexanal (D), and butanal, all of which constitute the overall flavor of mackerel before deodorization. The key flavor substances (VIP>1) after deodorization were ethyl isobutyrate, isoamyl alcohol (M), and 3-hydroxy-2-butanone, indicating that the rosemary extract deodorizing solution effectively improved the volatile flavor of mackerel.