"Metamorphosis" refers to the phenomenon of transformation between human and non-human. Folktale types of "Frog and Human Got Married" have been widely seen in various times and areas. The main plot of the stories is composed of "transformation between human and frog", each with its own characteristics. The study on Grimm's fairy tale "Frog Prince", the "Sacred Frog" series in folktales, and "Frog God" from "Liao Zhai Zhi Yiz", through the analysis of actors and action structural patterns, will unveil the social functions, literary connotations and symbolic meanings presented by the magical narratives.