Objective: Developing clean energy is crucial for achieving China's "double carbon" goals, prompting active investment in clean energy projects across the country. However, these projects face a complex external environment with many stakeholders, which makes large-scale grid integration challenging. Moreover, existing projects often suffer from issues such as insufficient energy allocation regulation, mismatched installed capacity and power demand, low economic efficiency in power transmission, and poor synergy effect among projects, mainly owing to inadequate design management. Although design management is vital in clean energy project management, a lack of research is observed from a collaborative perspective among participants. Methods: This study adopted a mixed research method that combined quantitative research and qualitative research. Quantitative data were obtained through questionnaire surveys, whereas qualitative data were obtained through semistructured interviews and case studies. Respondents included experienced professionals in clean energy project construction, such as owners, designers, suppliers, constructors, and supervisors. Herein, data analysis involved descriptive statistics, mean ranking analysis, difference testing, cluster analysis, and structural equation modeling. Results: The results show that partnering, feasibility studies, and owner's design management positively impact project performance through two paths: (1) partnering → feasibility study → design performance → project performance and (2) partnering → owner's design management → (feasibility study) → design performance → project performance. During the feasibility study, designers should deeply analyze the supply and demand of the clean energy power market, identify internal and cross-regional power consumption objects, and completely master the basic information of the design. They should rationally select sites, strengthen technical scheme demonstrations, fully consider site and surrounding area constraints, reasonably plan project resettlement and environmental protection, and ensure the project's economic feasibility. In the design process, owners should fully understand national and regional energy policies, deepen their understanding of the project objectives and design needs, and guide design development effectively. The contract should specify the design scope, depth, quality, and schedule requirements and reasonably define the responsibilities, rights, and obligations of all parties. It is crucial to establish a sound design management system, prepare a clear design schedule, and dynamically adjust the schedule as required. Implementing a sound design review, change, and optimization process, identifying design risks, and establishing corresponding control mechanisms are also essential. Developing operable design assessment indicators, reasonable reward and punishment measures, and a design interface management mechanism for stakeholders, along with actively applying information technology, is recommended. Combined with a case analysis, this study offers design management suggestions. Conclusions: This study proposes and validates a design management model for clean energy projects, revealing the considerable positive effects and pathways of partnering, feasibility studies, and owner's design management on project performance. Through questionnaires and interviews, this study deeply analyze the current state of the feasibility studies and design management, identifying key issues and factors to focus on in clean energy project design. The results provide theoretical and practical references for managing clean energy project design.