A methodology for automatic design optimization of CMOS analog cell circuits is presented. The proposed method uses symbolic analysis technique to generate exact analytic performance equations, describing the behaviors of circuits. The symbolic model is then passed to the genetic algorithm and is used as evaluating performance criterion. For the fixed topology, the algorithm sizes all elements to satisfy the performance constraints, thereby optimizing a user-defined design objective. Practical example shows that the method quickly designs analog cell circuits, closely meeting the specifications, and that it is a flexible and reliable design and exploration methodology.