According to the designing methods, computer animations can be divided into three kinds: frame-by-frame animation, keyframe animation and actor animation. Actor animations may meet the demand for real-time and interactivity. The model of actor is the key for actor animation. This paper mainly presents the modeling method of the actor in Net_Anim system developed by the author, which includes: the object-oriented model of the actor and the control scheme based on the model; the algorithms for synthesizing compound behaviors and some key problems to be considered; an example to demonstrate the compound actor with compound behaviors; the characteristics of Net_Anim and some problems to be solved in the future.