In this paper, the mechanism of image stimulation is systematically sorted out, and the role of image stimulation in the conceptual design process as well as the advantages of choosing images as stimulus inspiration are theoretically argued, providing theoretical support for image stimulation to stimulate creativity. Secondly, the influencing factors of image stimuli with different semantic distances in the design sketch stage and their effects on the design results were explored. The study verifies that image stimuli with different semantic distances affect designers’ behavioral performance during the design sketching process, which in turn affects the design results. Finally, a controlled experiment based on the Word2Vec word embedding method in the field of Natural Language Processing (NLP) was conducted to investigate the quantitative and qualitative effects of the image stimuli on the participants’ design outcomes during the sketching phase. It was found that the design results produced by semantically distant image stimuli outperformed those produced by semantically closer image stimuli in terms of quantity and originality, which verifies that image stimuli with different semantic distances affect design creativity.