In this paper, the novel design mode of human-aided design (HAD) is proposed to replace conventional computer-aided design (CAD). In HAD, computers can automatically complete the whole product design via a new isogeometric topology optimization (ITO), while humans just assist to slightly modify the design to meet requirements. An embedded domain ITO is presented to design complex models with irregular design domains, and editable geometric models of optimized results can be automatically generated based on layered ITO results. Three examples are tested to verify the proposed HAD mode, including a 3D cantilever beam with a regular design domain, an automotive part with an irregular design domain, and a Messerschmitt-Bölkow-Blohm (MBB) beam with a multiscale structure. The results demonstrate that the proposed HAD mode can automatically deliver high-quality optimized models; thus, it has great potential as a revolutionary technology to change the current design mode from CAD to HAD.