Abstract: City spatial data acquisition is the key to digital city. In allusion to the limits of traditional differential positioning model with 3DSurs, and with the development of regional continuous operational reference system or stations (CORS), 3DSurs precise positioning technique based on CORS is put forward. Firstly, we compute the approximate coordinate of 3DSurs. Then, we calculate the synthetical error correction of 3DSurs from CORS. At last, we calculate its coordinate precisely based on the front two steps. Taking the data from QDCORS for example to analyze the positioning precision of 3DSurs based on CORS, we find that the positioning precision is prior to 10 cm, and it can meet the need of city spatial data acquisition and positioning.