Abstract: The current constellation of BeiDou Navigation Satellite System (BDS) is described and the relationship between the accuracy of BDS relative positioning and its regional constellation characteristic is discussed in relation to the RDOP (Relative Dilution of Precision) and positioning errors. Experiments were conducted, the results obtained when using BDS relative positioning on short baseline in our country show that: (1) the accuracy of BDS relative positioning is better in the east-west direction than in the south-north direction and the elevation direction; (2) positioning errors in the south-north direction and elevation direction are negatively correlated; (3)the improvement of positioning accuracy reduces as the latitude increases; (4)BDS positioning accuracy is slightly less than GPS in the south-north direction; (5)the impact of BeiDou regional constellation on carrier phase relative positioning accuracy is slightly larger than the single-frequency pseudo-range differential.