Abstract: Indoor and outdoor seamless positioning is divided into two independent parts: indoor positioning and outdoor positioning. Indoor positioning usually selects (0,0,0) as the coordinate of the initial geomagnetic point, but this coordinate will be changed with the change of the experimenter or the change of the experimental site, which is not universal. Although GNSS cannot be positioned indoors, the geocentric fixed coordinates located outdoors with GNSS are unique and do not change. In this paper, the geocentric solid coordinate point of GNSS seamless positioning transition point indoors and outdoors is selected as the initial point. Geocentric solid is also used in the indoor positioning coordinate system, which can effectively solve the coordinate compatibility problem of seamless positioning indoors and outdoors and has a broader role.