Networks of reference stations play the role of sensors networks that continuously receive satellite signals. In this way, they provide data for many issues related to relative positioning. The density of reference stations network has an impact on measurements with kinematic techniques (e.g. RTK, NRTK) and the postprocessing of satellite observations recorded using the static technique. Networks of reference stations are divided according to their spatial range and the tasks they perform. The reference network can also be characterized by the network density. This article presents considerations concerning the determination of the average distance between the stations of national reference network, as well as between the stations of the higher accuracy network and the considered national network. The considerations relate to the example of the Polish ASG-EUPOS network. The average distance between the ASG-EUPOS network stations was determined in two-dimensional (2D) and three-dimensional (3D) space. It was determined that the average 3D distance between neighbouring ASG-EUPOS stations is approx. 42 km. However, in the case of determining the average distance between the network points using the sides of Delaunay triangles, this value is approx. 70 km. In the case of averaging the distance to six closest neighbours of each station, the obtained value was approx. 69 km. The areas of the ASG-EUPOS network characterized by an inconvenient location in relation to the EUREF Permanent GNSS Network class A stations, which is a network of a higher accuracy class, to which the ASG-EUPOS is related, were also indicated.