Summary: Providing a scientific understanding of the essence of man is one of the significant contributions of Marxist philosophy to the history of human thought. With a profound understanding of Marxist philosophy, Tran Duc Thao employed the dialectical materialist methodology to explain and substantiate the scientific value of Marx's concept of human nature. Therefore, based on the study of Tran Duc Thao’s works “The Formation of man” and “Problem of Man and Theoretical Antihumanism,” this paper aims to affirm and emphasize his crucial contributions to the study, defense, and development of Marxist philosophy, particularly the in-depth explanation of the scientific content of Marx’s Sixth Thesis on Feuerbach, a thesis that I.T. Florov considered, at first glance, to be very simple and obvious, yet profoundly deep and fundamental. Keywords: Human beings, essence of man, Trần Đức Thảo, theses on man