Objective To develop a questionnaire measuring the knowledge，belief，and practice of prone position ventilation for patients with ARDS among ICU medical staff，and to conduct reliability and validity testing. Methods Based on the knowledge，belief，and behavior theory model，an initial questionnaire was formed through literature study，theoretical analysis，expert interviews，Delphi expert consultation，and preliminary surveys. From October to November 2022，426 ICU medical staff from 7 tertiary comprehensive hospitals in Anhui Province were selected as the research subjects for reliability and validity testing. From January to February 2023，another 455 ICU medical staff from 7 tertiary comprehensive hospitals were selected as the survey subjects for confirmatory factor analysis. Results The final questionnaire consisted of three dimensions：knowledge，belief，and behavior，with a total of 41 items. The cumulative variance contribution rate of the three factors in exploratory factor analysis was 65.319%，and all fitting indicators in confirmatory factor analysis were within an acceptable range （χ2/df=2.504，RMSEA=0.058， RMR =0.014，IFI =0.933，CFI =0.933，PGFI =0.740，PNFI =0.846，PCFI =0.883）. Questionnaire Cronbach’s α coefficient was 0.982，the retest reliability was 0.995，and the split half reliability was 0.950. Conclusion This questionnaire has good reliability and validity，and is suitable for investigating the current status of ICU medical staff’s knowledge，belief，and practice of prone ventilation in ARDS patients.