Efficient spectrum allocation of cognitive wireless network is the key technology to dynamic spectrum access. Taking into account the needs of secondary users for the spectrum and the fairness allocation of the spectrum, mathematical model of spectrum allocation is given, and then it is converted into a constrained optimization problem with the goal of maximizing network profits. A chaos quantum clonal optimization algorithm is proposed to solve the problem, and then the convergence of the algorithm with probability 1 is proved. Finally, the simulation experiments are done to test the algorithm. The results show that compared with the color-sensitive graph coloring algorithm, the spectrum allocation based on genetic algorithm, and the spectrum allocation based on quantum-inspired genetic algorithm, the algorithm has good performances. It can achieve the maximization of network profits.