Due to the increasing number of functions of the Vending Machine, the VMC(Vending Machine Controller) is becoming more and more complex, so it is becoming more and more difficul to extend and maintain the developing method used before. According to the theory of FSM, this article suggests one FSM Model on the Vending Machine. The abstract model separates and divides the system into ones to establish a list of system states and transformations. If an event occurred, it would search the system transformation list by the system event and the current state. If there is a record that matches the state and event, then the state is transformed to the NextState defined in the record. Based on the experiment, the model can solve the big problem of the system and make the system development easier to maintain.