Abstract: Cell formation is the critical issue in cellular manufacturing (CM). Traditionally, cells are formed based on the partmachine relation and it considers no human operation. However, in practice, the operation effectiveness of different operators is different because of the different learning effectiveness. In this paper, cell formation problem is studied with human operator learning considered. An integer programming model by combining human operator learning curve is proposed for the cell formation problem. Then, the genetic algorithm (GA) is used to solve the problem. By this method, it not only assigns the parts into appropriate cells, but also assigns the operators into appropriate machines. In this way, the performance of the CM system is significant improved.