The principlism of informed consent emphasizes“rational egoism”and“justified action”. The “rational egoism”，where the doctor and the patient exist as separate individuals，leads to the disconnection of the doctor-patient relationship. “Justified action”makes people rely on external rules，leading to a weakening sense of internal responsibility. This paper attempts to address the limitation of the principlism of informed consent through Martin Buber’s relational ethics. Martin Buber distinguishes between“I - It”and“I - Thou”， emphasizing the importance of the dialogical communication between people. From the perspective of Martin Buber’s relational ethics，this paper discusses three specific ethical challenges of informed consent in xenotransplantation in terms of capacity，information，and decision - making factors. With the uncertainty of xenotransplantation，this paper proposes that informed consent should operate on the interplay between“I - Thou”and“I - It”，with the relationship of“I - Thou”as the core to foster a sense of positive responsibility toward others.