In the early design process, diverse design ideas are generated from a global solution search under unclear design conditions. Because it is difficult to apply conventional engineering design in the early design process, the emergent design system capable of generating various three-dimensional forms is proposed. Although this system appropriately set the parameters in every application cases, the system cannot determine whether the values of the obtained parameters are the best because the parameters are selected by trial and error. The research herein extracted the parameters that influence the diversity of form with the goal of devising the emergent design system that uses these extracted parameters to generate forms. Then these guidelines in this emergent design system were applied to a car body frame design. The results demonstrate that diverse solutions satisfying the mechanical properties can be derived, and thus confirm the usefulness of the guidelines.