Objective: To develop a questionnaire on oncology nurses’ knowledge-attitude-practice towards oral nutrition supplementation, and to test its reliability and validity. Methods: Based on literature review and Delphi expert correspondence, the initial questionnaire was constructed on the basis of knowledge-attitude-practice mode. A total of 265 oncology nurses from 5 tertiary care hospitals in Jiangsu Province were selected by convenience sampling method for pre-survey to test the reliability and validity of the questionnaire and form the final version. Results: The questionnaire included three dimensions: knowledge, attitude and practice, with a total of 43 items; exploratory factor analysis extracted a total of five common factors, with a cumulative variance contribution rate of 81.087%; confirmatory factor analysis results showed that the model fitted well.