Objective To retrospectively analyze 1 strain of Stenotrophomonas maltophilia (S. maltophilia) from hospital environment and 3 strains of S. maltophilia from clinical patients, and explore the homology between environmental and clinical S. maltophilia strains. Methods On September 3, 2021, environmental hygiene surveillance was conducted in the intensive care unit (ICU) of a hospital, and 1 strain of S. maltophilia was isolated. Meanwhile, S. maltophilia strains isolated from 3 patients in the ICU from June to November 2021 were collected. The above 4 strains of S. maltophilia underwent antimicrobial susceptibility testing, whole genome sequencing (WGS), multilocus sequencing typing (MLST) analysis, antimicrobial resistance gene detection, average nucleotide identity (ANI) value calculation, minimum spanning tree (MST) calculation, and phylogenetic tree construction. Results One strain of ST1244 S. maltophilia was isolated from the surface of B-ultrasound probe in ICU, which was consistent with the ST and resistance genes of S. maltophilia strain isolated from a patient’s specimen. The ANI va-lues of both strains were 100%, and there was no difference in their MST results. Phylogenetic tree analysis showed that the two strains were in the same evolutionary branch. Combining epidemiological information, it suggested that the strain from B-ultrasound probe might originate from contamination of the patient. Conclusion Patients with S. maltophilia infection can contaminate the surfaces of medical devices during usage, and sharing these devices could lead to the spread of pathogens within hospital.