Mycobacterium marinum infection often affects the extremities, causing single or multiple skin lesions. With the improvement of molecular detection technology and the clinical application of NGS pathogen detection, the diagnosis rate of Mycobacterium marinum skin disease is gradually increasing. This article reported the case of a 54-year-old man who was stung by a marine fish and gradually developed swelling and nodules on his right hand and right upper limb. He was diagnosed with Mycobacterium marinum infection by detection of the tuberculosis resistance gene dissolution curve of the pus and the identification of the bacteria. Oral rifampicin combined with clarithromycin and minocycline was given for anti-infection treatment. During follow-up, the abscesses and nodules gradually shrank and eventually disappeared. By presenting the diagnosis and treatment of this case, the understanding of this disease among clinicians can be improved to avoid misdiagnosis and missed diagnosis.