The paper explores a bionic design idea of product based on explanatory items and converts it into a bionic design method of product modeling. Based on the existing level of bionic design and Pierce symbol trivalence theory as a starting point, elaborate the interpretation of morphological symbols and functional symbols of organisms and products. Building the relationship between symbol interpretation of biological object and symbol interpretation of product object is established. At the same time, based on the mapping relationship, the method of bionic design of product form is proposed. Through the connection between symbol interpretation, establish the connection between the whale and two different products in a practical way, and derive two design schemes with typical biological characteristics and obvious product category indications. The design result of the bionic product will be directed to its biological and product objects as a symbol. The multilayer relationship of product bionic design established on the basis of interpretation items will improve the efficiency of integrating biological features and product features into the design results in the design process. The hierarchical relationship of bionic design based on explanatory items will improve the efficiency of integrating biological features into the product in the design process, and at the same time enable users to receive and understand the design significance of the product in a more accurate way.