As the formation of the Liangshan 梁山 fortress is the main theme in the Water Margin (水滸傳), we can understand more about the evolution of the novel by analysing the development of the fortress. The fortress is built in five different stages and its story can be divided into two main types. The major difference between the two types of the story is that the tavern of Zhu Gui 朱貴 in the first type is in the eastern side of the Liangshan Marsh, whereas the second type is on the southern side of the Marsh. Through the distinctive features in the Liangshan fortress, we have to believe that the Water Margin is composed of two different stories. In addition to the differences between the two types of the story, we find that there are also two forms of plots in the first type of the story seen in the discrepancy of the three taverns in the Marsh. Therefore, the Water Margin we read today is an edition which consists of two types and two forms of stories. It is a "mixed" edition and we believe that it is far different from the original one.