motahhari and kant are among the great thinkers of the islamic world and the west who have left innovative ideas in philosophy.the theory of nature is the central theory of motahari. he considers man to have three levels of temperament, instinct and nature and divides nature into two parts: cognition instinct and inclination instinct. most of motahari's innovations, especially in explaining issues such as god, immortality and morality, have been expressed in this part of the nature of tendency. as a great and influential philosopher in dealing with philosophy, kant critiques our metaphysical debates, especially issues such as god, the immortality of the soul, and freedom, and shifts the scope from theoretical reason to practical reason. motahhari theory of nature, especially the discussion of natural tendencies and discussions based on it; as the proof of god, the immortality of the soul and morality are highly comparable to kant's theory of practical reason, especially the subject of the postulates of practical reason; that is, freedom is the immortality and god. the purpose of this research is to apply the theory of motahhari nature and kant's theory of practical reason and to express their commonalities; that is, the similarity of infinite perfection with the summum bonum, the similarity of the method of proving immortality, proving god and the similarity of the position of moral philosophy according to motahhari and kant. in this regard, we have gone to the works of these two thinkers in a descriptive-analytical and comparative way.