Decision-making of the project delivery system (PDS) is an important link in the entire lifecycle of a project and is one of the critical factors leading to project success. Traditionally, PDSs are usually chosen based on the decision-makers' experience and knowledge and the project's information, without exploring the inherent dependencies between influencing factors and the PDSs. Presently, the researches on the factors affecting the choice of PDSs are primarily concentrated on the owner's characteristics, the project's characteristics, and the project's external environment. This paper mainly aimed at the owner's characteristics and researched the key factors affecting the decision-making of the PDSs; other two aspects will be studied in the subsequent research. Twenty-two influencing factors of owner's characteristics are summarized through a literature review, and 14 relatively important and high frequency factors with high frequency are chosen after discussion with specialists. Based on this, the owner's characteristics information from 76 Chinese construction projects, collected through questionnaires, is taken as the research sample. Then, rough set method is applied to reduce the redundant factors and result indicates that (1)responsibility, (2)the owner's willingness to be involved, (3)the owner's in-house technical capability, (4)risk allocation, and (5)the owner's willingness to control overdesign are the owner's five most key characteristics factors affecting PDSs decision-making. The research result provides a valuable reference for owner choosing appropriate PDSs and enriches the research methods in the field of PDSs. Although design-build (DB), design-bid-build (DBB), and engineering-procurement-construction (EPC) are deeply studied in the research reported in this paper, the other PDSs such as turnkey, construction management, and project management (PM) would be taken into consideration in further researches.