Abstract: There are small-and-medium-size manufacturing workshops that are operated manually. The operations of such manufacturing workshops are characterized as frequent order insert, variety of product types, small batch, and varying batch size. To operate such workshops well, it is necessary to design the production lines by considering the labors’ capacity attributes. The swarm intelligence method is adopted to design the production lines and labor allocation for such systems. In considering the features of different production operations and the labors’ capacity attributes, a modified ant colony algorithm is proposed for the problem. Numerical results are presented to show the effectiveness of the proposed method.