Attracting private sector participation in public sector participatory projects in the country requires an organizational framework tailored to the expectations of the private sector, and the purpose of this study as an applied, descriptive, exploratory and mixed research is to provide a public sector organizational model in order to attract private sector participation in public projects, that has been done in two stages, qualitatively and quantitatively. In the qualitative stage, the factors influencing the decision of the private sector investor in the form of codes, concepts, sub-themes and main themes have been determined with a phenomenological approach. Then, these organizational factors are classified into effective and efficient factors by DEMATEL method. The statistical population of the study consisted of private investors in public projects and experts of this era, in which 13 private investors and 9 experts were selected in a judgmental and purposeful manner and participated in interviews. Findings show that eleven major themes in the public sector including systems, advertising, business processes, organizational governance, human resources, communications, trust-building, branding, physical evidence of the organization, economic and social attractiveness of projects are influential in the private sector decision to partner with the public sector. Among them, organizational processes, human resources involved in the process of attracting partnerships, and organizational governance of the public sector are the most influential factors.