Breastfeeding is crucial for the health of both mother and baby, but improper breastfeeding posture and prolonged fixation often lead to skeletal and muscle pain in women, becoming the main reason for giving up breastfeeding. This study proposes a breastfeeding assistive device development strategy based on analysis of breastfeeding behavior, aiming to design an ergonomic sitting aid. By collecting data and conducting expert interviews, we collected information on the behavioral process of women’s sitting breastfeeding posture, and used the SAPAD framework method to conduct a multi-level analysis of sitting breastfeeding behavior, in order to identify the behavioral needs of women during sitting breastfeeding. During the development process, use TRIZ (Theory Problem Solving Method) to analyze the key contradictions in breastfeeding movements. And by analyzing the design principles and contradictions of existing nursing aids, the invention principles that solve the contradictions are obtained through the contradiction matrix, and the obtained invention principles are collected and sorted, and design suggestions are made based on the obtained invention principles. This study successfully proposed a development strategy for nursing aids, and the results showed that the development strategy based on nursing action behavior analysis can be widely applied in the design of nursing assistance products, thereby achieving the goal of mother infant compatibility. In the future, the development ideas and validation methods of this assistive device can also be further applied to other ergonomic designs, promoting the development of more ergonomic products.