In the evolution of Muslim’s philosophical thought, it was Sadr Al-Motaallehin who overcame many of complexities in philosophical studies on the soul and presented a new outlook. It is clear that Mulla Sadra’s philosophical psychology has been depended upon his special principals. The present research, therefore, is to explain the effect of Sadra’s theory of substantial movement, as one of his main philosophical principal, on his problems in the field including occurrence and continuity of human soul, the proofs supporting its uniqueness, its manner relation to body, the relation of soul to its powers, its connection to active intellect, the unity of knowing and the known, natural and arbitrary death, transmigration of soul, immateriality of imagination and corporal resurrection.