Objective: Severe fever with thrombocytopenia syndrome (SFTS) and hemorrhagic fever with renal syndrome (HFRS) usually have different infection routes, and coinfection is relatively rare. The clinical and etiological characteristics of coinfection by the two pathogens will provide important references for clinical diagnosis and treatment. Methods: Blood samples and epidemiological data on HFRS patients were collected and classified into severe and non-severe groups according to clinical severity. The differences in clinical characteristics and levels of pathogens were evaluated and compared. Results: A total of 22 HFRS patient cases were collected from December 2021 to October 2022. Of these patients, 16 were non-severe and 6 severe. Patients with rodent exposure history, muscle and joint pain, weight loss, pharyngeal and conjunctival hyperemia, and positive urine protein and antibody IGM had a high severe rate (P< 0.05). Molecular tests on blood samples showed that 3 of the 6 severe patients were positive for hantavirus, 2 of the 3 hantavirus positives were positive for bunyavirus. Conclusion: Severe HFRS patients have different epidemiological, clinical, and laboratory characteristics. The coinfection of hantavirus and bunyavirus leads to severe HFRS. These findings have implications and references for diagnosis and treatment of coinfected severe cases.