Background <p>As a non-invasive and economically feasible treatment method, prone position ventilation is a significant adjunctive therapy for patients with moderate and severe acute respiratory distress syndrome (ARDS) as well as those with severe pneumonia.</p> Aims <p>This study aimed to develop a Knowledge, Attitude, and Practice Questionnaire Related to Prone Positioning among Intensive Care Unit Nurses (PPICUNs-KAP) and assess the validation of this questionnaire in ICU nurses.</p> Methods <p>The draft questionnaire was formed by literature reviews and 2 rounds of expert consultations. This questionnaire was used to survey 267 ICU nurses from three tertiary hospitals in western Hunan Province, China in August 2024. Content validity and construct validity were evaluated by content validity index (CVI), exploratory factor analysis, respectively. Reliability was tested by internal consistency and test-retest reliability.</p> Results <p>After the exploratory factor analysis, three items(knowledge, attitude and practice) were excluded. Finally, the newly developed questionnaire included 42 items. It consisted of three dimensions: Knowledge (20 items); Attitude (7 items), and Practice (15 items). The Cronbach’s α and test-retest reliability of the questionnaire were 0.970 and 0.962, respectively.</p> Conclusions <p>PPICUNs-KAP is valid and reliable, and it is recommended for use in clinical practice and research to assess knowledge, attitude and practice related to prone positioning among ICU nurses.</p>