Objective To investigate the effects of adding beer and calcium lactate solution to the fermentation broth on the quality and volatile flavor substances of secondary fermented mustard greens.Methods Based on the inoculation of lactic acid bacteria into desalted mustard greens, cellar beer and pasteurized beer are added, respectively with calcium lactate solutions of different concentrations. Then, sensory evaluation is conducted on the secondary fermented mustard greens. Additionally, the pH, total acid, nitrite, reducing sugar content, and texture characteristics are determined during the fermentation process. The volatile flavor components of mustard greens are comparatively analyzed by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS).Results The addition of beer can improve the flavor of secondary fermented mustard greens. A total of 144 volatile flavor components are detected, mainly alcohols, esters, and acids. Among them, the alcohols and esters of higher content are those with mild aromas, such as floral, fruity, and fatty. The addition of calcium lactate solution can significantly increase the crispness and hardness of secondary fermented mustard greens.Conclusion Adding beer and calcium lactate solution to secondary fermented mustard greens can not only enhance the volatile flavor substances of fermented mustard greens, but also effectively improve their crispness and hardness.