In recent years, due to a lack of effective cooperative management measures, prefabricated building projects face many obstacles. The designers of prefabricated building projects usually do not consider the convenience of manufacturing and construction, but only focus on the national specifications, prefabrication rates, and the need for construction units. It can lead to an inefficiency caused by overwhelming design variations and remediation of defects, which are relatively common in current practices. Although many factors are affecting the efficiency of prefabricated building projects, it is a current gap to assess which of them is/are more critical. To address the gap, this paper identifies 18 collaborative state parameters (i.e. synergetic state parameters) of prefabricated construction projects based on interview results with 20 experts and, furthermore, results of 126 structured questionnaires. Eventually, based on synergetics, the key factors (i.e. synergetic order parameters) affecting the collaborative management of prefabricated construction projects are identified by using the main melody analysis. This study concluded that information collaborative platform, project organization structure, and collaborative benefit (in the order of importance) are the key factors influencing the efficiency of prefabricated building projects. The research finding can help the managers of all parties in the construction industry to understand the decisive factors to ensure efficient collaboration in prefabricated construction projects.