As an important part of Beidou Navigation Satellite System (BDS), Beidou Satellite-Based Augmentation System (BDSBAS) is not only an important means to provide a high-integrity navigation service, but also an important measure to cope with the fierce international competition. BDSBAS ground monitoring station is responsible for the acquisition, analysis and pre-processing of satellite signals. As the provider of key data, site selection is very important in the construction of the BDSBAS, which directly affects the performance of the BDSBAS. The impact of the monitoring station site selection, such as electromagnetic interference, GNSS antenna cover angle, the number of multipath interference, the Dilution of Precision (DOP) and the measurement accuracy has been analyzed. Combining with the theories and real data, a comprehensive evaluation method based on order of ideal solution algorithm is proposed, to solve the problem of optimal site selection for monitoring stations and provide reference for subsequent site selection.