In this study, we have investigated etymology of verb structure in inscriptions with a descriptive-analytical approach in order to study verb structure and grammar and their position in the sentence referring to the inscription. Regarding data collection, we have used library research and have presented grammar of the verbs through taking notes. In order to optimize studying etymology and correct translation of the words, we have adopted ancient eras so as to describe essential points. Verbs are specified and the tenses are analyzed. Studying the verbs and its etymology is the most important in terms of data collection. We have intended to study similarities and differences between verbs and its evolution since ancient era to middle-era Persian and Askani Pahlavi in the inscription of Shapur 1 Cube of Zoroaster. In this article, verbs in the inscription of Shapur 1 in Cube of Zoroaster as well as its grammar is addressed. The results show that verb in ancient Persian language through to middle Persian has experienced alterations. During these alterations, from ancient Persian to middle Persian and Askani Pahlavi, perfect present systems, past and future and initiative, wish and intensifications are all disappeared. The only system known as present tense has evolved and gained popularity.