The paper aim to introduce affordance into the user demand analysis stage to accurately locate user needs and product elements, reduce the deviation between the expression of product design elements and user understanding due to inaccurate demand extraction, thereby improving the usability and ease of use of the product.Firstly, the paper obtains the initial description of user needs through qualitative research methods such as questionnaire surveys, leading user interviews, and establishment of product evaluation databases, classifies them with functional affordance, behavioral affordance, cognitive affordance and sensory affordance , and summarizes and extracts the design requirements elements. Secondly, the paper uses the fuzzy Kano model to quantify and filter the extracted design elements, and uses the analytic hierarchy process to determine the importance of the design elements. Finally, the paper applies the selected design elements that meet the user's psychological expectations in design practice. The paper constructs a user demand analysis method based on affordance and completes the design of a multifunctional portable picnic box. According to the evaluation indicator of product design affordance elements, the paper completes the scheme design evaluation, verifies the feasibility and effectiveness of the design results and provides a reference for the needs of research and design innovation of similar products.