Dual-polarized reconfigurable intelligent surfaces (RISs) increasingly play significant roles in reshaping wireless transmission environments. In this Letter, we propose a design method for dual-polarized RIS elements. This proposed method develops an equivalent multiport model to quickly calculate reflection electromagnetic (EM) responses of the elements containing multiple structural parameters. Moreover, the genetic algorithm (GA) is utilized to optimize the structural parameters to meet design specifications. A 1-bit dual-polarized RIS is implemented for verification. The simulated and experimental results show good consistency with the calculated results. The proposed method significantly conserves design resources, promoting the development of dual-polarized RISs.