Complex products have multiple external stakeholders, and their influence is different due to different levels of power and interests. At present, enterprises mainly focus on a small number of influential external stakeholders, while ignoring others, which will affect the satisfaction of different stakeholders with complex products and is not conducive to improving the market competitiveness of enterprises. In addition, a large number of unstructured data related to complex products contain much information about the stakeholders' requirements. This paper proposes a requirement mining and analysis method, which determines the importance of top-level technical indicators by considering external stakeholders and their requirements. The proposed methods start with determining the importance of external stakeholders of complex products through the Power/Interest matrix. Afterward, based on the unstructured data requirement mining model, the requirements and importance of external stakeholders are determined from different data sources. Finally, according to the results of external stakeholder analysis and requirement mining, the house of quality is constructed to accurately map the multiple external stakeholders' requirements to the importance of the top-level technical indicators of complex products, which provides a basis for the functional design of complex products. The proposed method is verified by a case study of subway design.