Abstract: A lot of level control systems can be seen as a kind of liquid storage vessel system，and it is practical to study the modeling methods for the system.In this paper，two modeling methods for this vessel system are illustrated by the example of a tank level control system，that are a novel fuzzy inference modeling method and a mechanical modeling method.A series of experiments are designed to analyze this two modeling methods，and based on the simulation result and practical experiments，the characteristics of these modeling methods are addressed and their applying field are clarified.