Objective To analyze the clinical characteristics of patients with brucellosis complicated with pleural effusion, and provide reference for clinical diagnosis and treatment. Methods Medical records of four patients with brucellosis complicated with pleural effusion in Hulunbuir People's Hospital from January 2013 to December 2020 were analyzed. General data, epidemiological history, clinical characteristics, laboratory examination and curative effect were analyzed retrospectively. Results All four cases of brucellosis complicated with pleural effusion were male, the youngest was 22 years old and the oldest was 62 years old. All patients had symptoms of fever, fatigue, accompanied by chills, sweating, lumbago, pain in back and bilateral flanks, cough, expectoration, chest tightness, shortness of breath, and dyspnea. Bengal plate agglutination test (RBPT) and standard tube agglutination test (SAT) of serum and pleural effusion were positive in all patients, and Brucella was isolated from blood culture and pleural effusion of one patient. C-reactive protein and erythrocyte sedimentation rate increased in all patients, and tuberculin test was negative or weakly positive. Pleural puncture was performed to extract yellow liquid from pleural effusion in three cases and purulent in one case, the effusion was medium or above, which was exudate. The short-term effective rate was 100% after patients were given 12 weeks or more of enough combination therapy with antimicrobial agents. Conclusion Incidence of brucellosis complicated with pleural effusion is low, when patient has fever, fatigue, sweating and respiratory system discomfort, clinician should ask patient about the epidemiological contact history in detail, considering the possibility of brucellosis, early diagnosis and treatment can lead to a good prognosis.