Abstract: To enhance the comprehensive utilization efficiency of large yellow croaker and pickled potherb mustard, and to clarify the processing technology of pickled potherb mustard-large yellow croaker as well as its flavor changes during processing, this study took large yellow croaker and pickled potherb mustard as raw materials. The cooking process of pickled potherb mustard-large yellow croaker was optimized through single-factor experiments and orthogonal tests. Gas chromatography-ion mobility spectrometry (GC-IMS) and high-performance liquid chromatography (HPLC) were employed to analyze the flavor profiles of fish meat samples and soup samples at different processing stages, including pickling, frying, and cooking. The optimal formulation for potherb mustard-large yellow croaker consisted of 30% potherb mustard, a steaming time of 8 min, a fish-to-liquid ratio of 1:1.75, 0.75% salt, which achieved the highest sensory score (0.8466). GC-IMS analysis identified 46 volatile organic compounds (VOCs) during processing, including 11 esters, 10 ketones, 7 alcohols, 5 aldehydes, 6 sulfur-containing compounds, 2 terpenes, and 5 other compounds. A total of 17 VOCs were screened by multivariate statistical analysis and could be used as key differential compounds. These included 6 esters, 3 ketones, 2 alcohols, 1 aldehyde, 1 sulfur-containing compound, and 1 acid. They were mainly responsible for significant differences in fruity, pungent, garlicy, sour and other odor attributes.The addition of preserved pickled potherb mustard imparted distinct fruity and sweet aromas to the dish while reducing undesirable fishy off-flavors. The contents of non-volatile compounds and the taste activity value (TAV) varied across different processing stages. After deodorization, frying and cooking treatments, the total amino acid content in fish samples was higher than that in raw fish, while the 5'-IMP content was the highest in raw fish. Following cooking, both meat and broth samples containing pickled potherb mustard exhibited higher equivalent umami concentrations than fish meat or broth alone, indicating that pickled potherb mustard enhances umami perception. Overall, the flavor profile of large yellow croaker undergoes dynamic changes during processing, and the incorporation of pickled potherb mustard significantly enriches the dish's aromatic and taste characteristics. These findings provide theoretical insights for the deep processing and pre-prepared aquatic foods.