Understanding the mythological background of epic characters helps us to analyze their functions in literary texts. Studying the functions of Vayu and the existence of some similarities between this lord and Kai Kā vus provides a comparative investigation of these two mythological characters. Kai Kā vus, as described in Shā hnā meh, is one of Iran's greatest epic kings and has a mythological background. Vayu is the god of wind and air that rules the empty space between heaven and earth. The present study, by using descriptive-analytical method, has found the similarities between the two characters. They are as follows: having ambitious personality, having divine light, having magic-medicine power, being warlike, being messenger of death, having a windy nature and being the father of first man. Although there are slight differences, the similarities between the two mythological characters make us think that the Kai Kā vus is a transformed and human form of Vayu. The purpose of this research is to present Kai Kā vus' godly background, his epic behavior and his multi-dimensional character in Shā hnā meh.