Abstract: BeiDou navigation satellite system (the BeiDou system) is the only PNT (Positioning, Navigation and Timing) resource in China that has coverage of the globe and near-Earth space and provides continuous high-precision, low-cost positioning, navigation and timing solutions for users in a unified spatio-temporal benchmark. As an important spatio-temporal benchmark transmission system, the BeiDou system is the most important resource for the national PNT system to provide a PNT capability under a unified spatial-temporal benchmark. This paper proposes the concept, composition and development model of the space-based PNT system design based on the BeiDou system with all its space characteristics, as well as the advantages of the system. It opens up a new direction for the construction of China’s PNT system and expands a new horizon in the research of a PNT system in China.