Mood is one of the grammatical categories of verb, which has been generally used by Persian and Russian linguists in the sense of declarative, imperative and potential. The language elements are different in representing these concepts in Persian and Russian language. The potential mood is referred as an unreal case in both languages and the possibility of its occurrence is both in past and future tense. To express it, not only verbs but other language elements are also influential. The purpose of this research is to compare the language element for expressing the Potential mood and also to evaluate the syntactic structure, used in Russian and Persian language, and finally to find language distinctions and similarities. Since, in Persian language there are many grammatical elements to express the potential mood, the grammatical meanings of Tense, Person, and Number is accurately defined in the verb of the supposed sentence in Persian. While there are no necessary grammatical elements in the potential mood of Russian verbs, the mentioned meanings are not available in Russian language.