Abstract: Mega construction projects serve as critical platforms for technological innovation and key drivers of value creation. However, the efficiency and effectiveness of technological innovation within such projects are often suboptimal. Collaboration among innovation stakeholders is an important approach to addressing the challenges of technological innovation in mega construction projects. Currently, there is a lack of systematic research in academia on the influencing factors of technological innovation collaboration in mega construction projects. Therefore, this study adopts the grounded theory qualitative research method to identify influencing factors and construct a theoretical model, based on 208 labeled data items obtained from the Hong Kong-Zhuhai-Macao Bridge project case. The results indicate that external environmental factors, engineering and technical factors, innovation risk factors, and innovation organizational factors are the four main categories of factors influencing technological innovation collaboration. Subsequently, the internal correlations among the four categories of factors are further analyzed, and a theoretical model of influencing factors is constructed. This study enriches the theory of technological innovation collaboration in mega construction projects and provides practical guidance for achieving innovation and high-quality development in such projects.