Abstract: By reviewing the primary project management modes, two mechanisms, that is, formal mechanism and relational mechanism, that to cope with the uncertainty in project management from a relationship-building perspective are identified. Furthermore, by exploring the sources of the uncertainty in project management on the basis of principals of HEXIE(harmonious) management theory to cope with uncertainty, it is found that the optimal configuration of formal and relational mechanisms depends on the types of uncertainty involved in project management; formal mechanism is best suited to object-based uncertainty, and relational governance is best suited to human-based uncertainty, while the complement between the two mechanisms is suited to the mixture of both object and human-based uncertainty according to the critical task of the project. Finally, an analytical framework to cope with the uncertainty is developed and future research directions are discussed.

Key words: uncertainty, contract mechanism, relational mechanism, HEXIE(harmonious) management theory, mechanism matching