Objective To provide a scientific basis for the prevention and control of brucellosis by epidemiologic investigation and analysis of a familial cluster of brucellosis case. Methods The field epidemiological investigation method was used to analyze the pathogenesis and source of infection of the three cases, and the tiger red plate agglutination test and tube agglutination test were used to detect the antibody. Results On April 17, 2017, the Xianghe County Center for Disease Control and Prevention in Langfang, Hebei province reported three cases of clinical diagnosis of brucellosis in Baodi district. There were three cases of infection with both tests positive in the epidemic. The source of infection was sick animals, especially miscarriage tissue from the sick ewe. The patients had no effective protection in daily work. Conclusion The awareness of protection during daily work and related knowledge and skills of identification of animals with brucellosis should be improved among employees to effectively cut off the transmission route of brucellosis and thus achieve the prevention and control of this disease.