Abstract: The idea and method of realizing Iteration Function System, Graphics Iteration System and L-system in Flash, are explored in this article. The key researching problem is the method of generating fractal trees based on Flash., and the fractal trees are constructed by combining the Iteration Function System and the film editing technology in Flash. Furthermore, two methods of generating fractal animation in Flash are studied. Dancing tree is realized by adding the functions of mouse interaction, moving record, replaying in films and by modifying the parameters.