Objective To develop an advance care planning (ACP) intervention program for adolescent and young adult (AYA) cancer patients in China, and to improve the effectiveness of ACP in this population.Methods Based on the transtheoretical model, the ACP intervention program for AYA cancer patients was developed through literature review, focus group interviews, and semistructured interviews.Then,15 experts were consulted using the Delphi technique.Results All experts returned their questionnaires in the tworound consultation, with the authority coefficient of 0.865.The Kendall′s coefficients of concordance were between 0.238 and 0.394 in round 2 (all P＜0.05).Final version of the ACP intervention program included five stages:precontemplation, contemplation, preparation, action, and maintenance. And specific implementation strategies were provided, including intervention timing, themes, contents, objectives, methods, and evaluation indicators.Conclusion The ACP intervention program for AYA cancer patients based on the transtheoretical model is wellaccepted by experts.However, it remains to be validated in further studies.