This paper reports the clinical characteristics as well as diagnosis and treatment processes of a patient with mixed pulmonary infection of Rhizopus microspores and Aspergillus. The patient had history of type 2 diabetes mellitus, and was admitted to the hospital due to diabetes ketoacidosis complicated with pneumonia. Clinical manifestations included cough, expectoration, and fever. Imaging examination showed inflammatory lesions of bila-teral lungs (mainly in the right lung) associated with local consolidation. Bronchoalveolar lavage fluid (BALF) smears and galactomannan antigen test (GM test) were both negative. Nucleic acid sequences of Rhizopus microspores and Aspergillus were detected by metagenomic next-generation sequencing (mNGS) at the early stage, while complicated infection of Klebsiella pneumoniae and COVID-19 were also found. The final pathological diagnosis was pulmonary mucormycosis combined with invasive pulmonary aspergillosis. The patient achieved clinical curing through the combination of isaconazole antifungal treatment and lobectomy of the right middle-lower lobes.