Abstract: Artificial life and artificial intelligence are combined and applied to computer animation. In the computer animation created by artificial life, some behaviors of artificial life in virtual environment are pre-defined by programmers, and some are nondeterministic arise at random. Artificial fish is researched as an example, and a cognitive model of the nondeterministic behaviors of intelligent life is presented. The subset searching mechanism is used to improve the searching efficiency. It is shown by the simulation example that with help of the cognitive model, intelligent life is capable of handling some nondeterministic events.