Abstract: Indoor and outdoor seamless navigation and positioning is the cornerstone of everything is interconnected, and it has broad market prospects and application value. However, there are still many knotty problems for the seamless integrated navigation of indoor and outdoor transition area. In order to solve those problems, this article improves the indoor and outdoor seamless linking method of Beidou satellite navigation system Ultra-wideband (BDS/UWB) combined positioning from three aspects: The first is to propose an indoor beacon absolute positioning method based on internal and external citation methods, which to solve the problem of the coordinate reference unification of indoor and outdoor positioning results; the second is to propose an optimal layout scheme of indoor beacon based on PDOP stable change, which to improve the positioning accuracy and beacon availability in the transition area; the third is to introduce an adaptive weight factor to solve the reasonable weighting problem of observations of BDS/ UWB combined positioning. It is verified through specific experiments: 1) using the indoor beacon absolute positioning method based on indoor guidance and outdoor guidance method, it is possible to achieve the indoor and outdoor coordinate reference unification, which significantly improves the convenience of users; 2) the optimal layout scheme of indoor beacon can effectively improve the positioning accuracy of the transition area. compared with and without UWB beacons, the BDS/UWB combined positioning accuracy can be improved by at least 355%; 3) the adaptive weight factor can adjust the observation weight ratio of different time and different types in real-time, and it enhances the efficiency of observation information utilization. Compared with BDS in open area, its positioning accuracy can be improved by at least 22.5%.