Abstract: The chaos-Monte Carlo algorithm(CMCA) was proposed for solving chemical equilibrium of complex system.By introducing random well-distributed points into the Monte Carlo algorithm, this new approach showed good convergent probability and high-speed.Equilibrium composition of some complex systems,such as methanol synthesis, ammonia oxidation, and Claus process were calculated.The results showed good agreement with Liu Xiaodi’s and Xu Jinhuo’s calculations.Compared with the gradient method, the genetic algorithm and the modified genetic algorithm,the CMCA is simple, general and insensitive to initial value.It is an efficient algorithm based on the theory of minimization of Gibbs free energy to solve chemical equilibrium of complex system.