To compare and analyze the positioning performance of BDS-3 and GPS in Polar Regions, based on STK software, the simulation constellations of BDS-3 and GPS are established respectively. Four observation stations were selected in north and south poles, and the satellite visibility and GDOP of each station were simulated and analyzed. The results show that the average number of visible satellites of BDS-3 in Polar Regions is about one more than that of GPS. The GDOP value of BDS-3 remains at an "excellent" level in north and south poles, which is better than GPS and changes steadily. On the whole, the positioning performance of BDS-3 in the Polar Regions is better than GPS.