Abstract: This paper studies the mathematical model of Multiband Joint Detection (MJD). The MJD problem can be formulated as a constrained optimization problem with the goal of maximizing the aggregated opportunistic throughput of a cognitive radio system under some constraints on the interference to the Primary User (PU). An Immune Clone Algorithm (ICA) is proposed to solve this problem. The performance of the proposed method is analyzed and compared with the Genetic Algorithm (GA) based technique through computer simulations. Experiment results show that the proposed method offers higher aggregated opportunistic throughput rates under the same interference to PU than GA, and the results demonstrate the stability and effectiveness of the method.