This paper presents a new 3D model-based gesture tracking system for controlling multimedia player in an intuitive way. The motivation of this paper is to make home appliance aware of user's intention. This 3D model-based gesture tracking system adopts a Bayesian framework to track the user's 3D hand position and to recognize meaning of these postures for controlling 3D player interactively. To avoid the high dimensionality of the whole 3D upper body model, which may complicate the gesture tracking problem, our system applies a novel hierarchical tracking algorithm to improve the system performance. Moreover, this system applies multiple cues for improving the accuracy of tracking results. Based on the above idea, we have implemented a 3D hand gesture interface for controlling multimedia players. Experimental results have shown that the proposed system robustly tracks the 3D position of the hand and has high potential for controlling the multimedia player.