On the literary image of pigs, it is the most representative of the lecherous image of Zhu Bajie in "Journey to the West". That is often thought to be derived from "JhuBi JinLing" in the SouShenJi. The sow monster of JhuBi JinLing is one of the important sources about the image of "the Pig is Lustful". However, the image is not always the same, which has followed social environment's change, religious influences, the literature popularizations, and other factors. The lecherous image of the pig became a conscious identification of the group and became a symbol of irrational lust that would later become conventional. This article takes the external appearance and inner characteristics of Zhu Bajie in "Journey to the West" as the idea, which will focus on two points, one is according to myths and legends, explore the impact of the morphological changes from "pig" to "human" on the development of the image of pigs. The other is based on the short strange stories in classical Chinese of the Six Dynasties and the Tang Dynasty, which analyzes the development of the image of the pig from "sexual lewdness" to "lecherousness".