Proceeding of the Joint International Symposium on Deformatuon Monitoring. 2-4 November, 2011. Hong Kong. China. Report. The stability of the base stations is the basis of operation for all kinds of GPS CORS network. This paper presents the stability analysis results of all points of Beijing CORS net (shown in Fig. 1) with GAMIT. The result show that the trend of the station's coordinate is linear, and the coordinate residual changes randomly(shown in Fig.2 and Fig.3). The accuracy of N, E components is better than 2mm, and the elevation accuracy is better than 5mm. Base stations are stable.