Abstract: According to the construction situation and development strategy of BeiDou Satellite Navigation System, the construction of Beidou Satellite Navigation System in China has entered the third stage. Based on the data of IGS continuous tracking station, this paper firstly analyses the data quality of BDS-3 signal, then analyses the positioning accuracy of BDS-3 quasi-single point, and compares it with the positioning accuracy of BDS-2 standard single point. The results show that the data quality of BDS-3 is better in the observation area, and the positioning accuracy of BDS-3 single point is better. The positioning accuracy of the system is better than that of BDS-2.