In this writing the thoughts and ideas of Duns Scotus on the existence of God is studied and the influence of Ibn Sina on it from a realistic angle on the basis of documents will be elucidated. Scotus in his discussion of proving the existence of God in view of presuppositions or premises and principles and even by way of the structure of argumentation is quite under the influence of Ibn Sina: Following Ibn Sina, Scotus regards Aristotelian argument from the first mover as invalid, begins his argument with "existent in general", considers the concept of existent as univocal, takes possibility in the meaning of contingency, regards God as efficient cause in the real sence and bestower of existence and as prefect, creative cause, and in his argument he uses the middle and around term.Besides the influence of Ibn Sina on Scotus there is similarities and differences among the ideas of these two thinkers: the result of the arguments of both thinkers in a God with similar characteristics philosophically, but different in religious point of view. In their argument to the existence of God as well Ibn Sina and Scotus are alike, except that in the philosophy of Ibn Sina in this way efficient cause is first proved, but in Scotus by the same way of argument the treefold supremacy of God as a whole is proved.