Demoralization syndrome and suicidal ideation are important risk factors affecting the quality of life and prognosis of cancer patients, and with the development of palliative care, comprehensive and precise suicide prevention has become an important prerequisite to improve the quality of life of the patients. The relationship between demoralization syndrome and suicidal ideation has not yet been clarified, and still needs further research. In this article, from the perspective of the concepts of demoralization syndrome and suicidal ideation, their relationship, possible action mechanism, and prevention and intervention strategies, we summarized the potential mechanism of their interaction in cancer patients, aiming to provide a reference for identifying high-risk population and implementing early intervention.