目的　探讨肺孢子菌肺炎的病因、临床表现、病原学诊断和治疗。方法　回顾分析1例肺孢子菌肺炎患儿的 临床资料。结果　患儿，男， 2个月20天，临床表现为慢性咳嗽、气促、烦躁、低氧血症；肺部影像呈双肺弥漫性浸润改变； 经支气管镜术取肺泡灌洗液进行宏基因高通量测序后证实为肺孢子菌感染。确诊后予甲氧苄胺嘧啶-磺胺甲噁唑（TMPSMZ）治疗，临床症状基本消失，肺部 CT明显好转。结论　肺泡灌洗液行宏基因高通量测序可诊断肺孢子菌肺炎。

　Objective　To investigate the etiology, clinical manifestations, etiological diagnosis and treatment of pneumocystis pneumonia. Methods　The clinical data of a child with pneumocystis pneumonia were retrospectively analyzed. Results　A male infant, aged 2 months and 20 days, presented with chronic cough, shortness of breath, irritability, and hypoxemia. Pulmonary imaging showed diffuse infiltration of both lungs. The metagenomic next-generation sequencing of bronchoalveolar lavage fluid by bronchoscope confirmed pneumocystis infection. Clinical symptoms of the patient disappeared and exudation of lung CT absorbed after treatment with trimethoprim-sulfamethoxazole. Conclusion　Infants should be alerted to pneumocystis pneumonia when having recurrent cough, shortness of breath, hypoxemia and diffuse infiltration in both lungs. Metagenomic next-generation sequencing with bronchoscopic alveolar lavage fluid is a better method for pathogenic diagnosis of pneumocystis pneumonia.