The Beidou Regional Satellite Navigation System (BDS) has an uneven distributed constellation, containing five satellites in geostationary earth orbit, five in inclined geosynchronous orbits and four in medium earth orbits. With this hybrid constellation, the quantity and the geometrical structure of observed BDS satellites are different at different latitudes. The latitude effect in BDS application performance of positioning and navigation; In this paper, theoretical models and actual observations are described to analyze the difference in quantity and geometrical structure of observed BDS satellites and the performance of positioning and navigation at different latitudes. An experiment was conducted at different latitudes with receivers from separate companies. The result shows the latitude effect and impact in BDS applications, which means BDS positioning accuracy decreases with increasedlatitude. In contrast, there is no obvious latitude effect in Global Positioning System (GPS) applications. The implementation of BDS/GPS data fusion weakens latitudinal impacts on the results and improves the accuracy and reliability of navigation and positioning services.