Cognitive Radio (CR) has been regarded as a promising technology to improve the spectrum utilization significantly. One of the considered issues in CR is the allocation of frequency channels between its users. In this paper, at first, the model is presented, second, new spectrum assignment methods based on Artificial Bee Colony (ABC) algorithm is proposed. In this algorithm in order to decrease the search space is proposed a mapping process between the channel assignment matrix and the position of the bees of ABC based on the characteristics of the channel availability and the interference constraints. The Results show our proposed method has results mush near to the optimal values, which are calculated using exhaustive search. Corresponding results show that our proposed method fast converge in maximizing three objective functions which are: Max-Sum-Reward (MSR), Max-Min-Reward (MMR), and Max-Proportional-Fair (MPF); this feature makes our proposed method useful for practical applications.