To systematically extract traditional patterns, apply divergent thinking, and integrate AI tools into the design of related cultural and creative products, this study analyzes the theories of semiotics and extension theory, combining them to form a cohesive framework. Using extension semiotics, the study outlines a process for the extraction and application of traditional patterns and integrates modern AI tools for cultural and creative product design. A workflow for innovatively designing traditional patterns using AIGC (AI-Generated Content) drawing tools is established. Taking the application design of Suzhou Garden lattice patterns as an example, the study employs semiotics to sort out the three elements and establish a pattern sample database. Subsequently, an extension model is constructed to encode the samples and create a “gene pool” for pattern redesign through extension transformations. Finally, Midjourney is used as an AI drawing tool to assist in the design of cultural and creative products. The study results in a planar design scheme for lattice patterns. This methodological process provides a general approach for extracting and redesigning traditional patterns using AI tools.