The chaotic ant swarm algorithm is a chaos optimization algorithm based on swarm intelligence theory which was inspired by the chaotic and self-organizing behavior of the ants in nature. It includes both effects of chaotic dynamics and swarm-based search. Through the construction of a suitable fitness function, the problem of parameter estimation of the chaotic system is converted to a problem of parameter optimization which could be solved via chaotic ant swarm algorithm. Chaotic ant swarm algorithm has the ability of global search. A numerical simulation on the well-known Lorenz chaotic system is conducted. Simulation results show that the proposed method is effective in parameter estimation of the chaotic system.