Abstract: In real-time deformation monitoring applications, ambiguity cannot be quickly and reliably resolved under poor conditions using dual-frequency observations. In this paper, we analyze the single epoch ambiguity resolution success rate of GPS and BDS system under different calculating models. A new method based on triple-frequency BDS observations is proposed to fix the original ambiguity based on the TCAR (three-carrier ambiguity resolution. Sidereal day filtering based on observing domain reduces multipath errors in wide-lane observations under conditions where the original ambiguity cannot be fixed reliably. Real data is used to test the method, results show that the success rate and accuracy are improved in comparision to the dual-frequency models. A success rate of 100% was achieved using the wide-lane ambiguity resolution, and the RMS values for the wide-lane fixed solution reached 7 mm after filtering.