The work aims to propose a method of Grand Canal cultural creative product design based on the extension semantic analysis to address the uncertainty of the Grand Canal cultural resources in the design transformation. First, a representative type of Grand Canal culture was selected to analyze its cultural characteristics and extract the semantics of the words to further establish an extension representation model; Then, the semantics of words was transformed into graphical semantics to calculate the extension design interval of characteristic words and quantificat the relationship between culture and characteristic words; Final, new design elements were obtained through the evolution of shape grammar, to carry out design practice for verification with the Tianjin Beichen peasant painting as an example. The results show that extension semantic analysis has strong guidance and feasibility in cultural creative design. It can provide research ideas for the design and development of linear cultural resources such as the Grand Canal culture.