Behavior animation of virtual human is an interesting branch of computer animation in recent years. Many researchers focused on the local expression animation of virtual human emotion

such as facial animation system

and did not consider the reason of emotion to a specific virtual scene. Emotion is the result of interaction between virtual human and virtual environment

the emotion of virtual human has not gained clear description up to the present in the field of computer animation. This paper presents an animation model of emotional behavior for virtual human on the basis of psychology theory. First

this paper introduces the concept of emotion set and emotion expression sets

and sets up a function from emotion state to emotion expression; Second

this paper pays attention to the reason of emotion and introduces the concept of emotion origin

if the strength of an emotion stimulus is bigger than the resistive capacity of an emotion

then the emotion will occur; Third

the emotion state can be expressed as a finite state machine (FSM)

and an emotion transfer flow is presented. As a result

a demo of virtual human emotion behavior is realized on personal computer by calling the Microsoft Direct3D API with the programming visual c.