Abstract:The classical natural philosophy of Yi people affirms that all creaturesꎬ including human beingsꎬ are involved in the cycles of life and death. It holds that the existence of life in nature and even human beings is a unity of oppositesꎬ in which life and death depend on each otherꎻ that the evolvement in human concepts of life and death mirrors three stages in the progress of human society---ignoranceꎬ barbarism and civilizationꎬ which reflect the development of human society from junior form to senior formꎻ and that life and death of every individual are subjected to his worship toward souls and ancestors. Metempsychosis is manifested in Yi people′s concept of life and deathꎬ as their saying goesꎬ life is the prelude of deathꎬ and death is the turning point of life. Yi′s knowledge of life and death echoes both idealistic view of life and death and materialistic epistemologyꎬ which depend on and at the same time contradict to each otherꎬ a classical example of dialectical unity.