Abstract:We establish a stable reference frame for the northeast China region(NEChina20) using continuous GNSS observations from 2012 to 2019. NEChina20 is aligned in scale with IGS14. The two coordinate systems are tied at epoch 2020.0. The frame stability(accuracy) of NEChina20 is about 0.5 mm/a in the horizontal direction and 0.6 mm/a in the vertical direction. The stability of the reference frame degrades with the extension of the time window and the expansion of the coverage area. We suggest that the usage of NEChina20 be limited to the Northeast and adjacent areas within the time window from 2005 to 2025. We have also developed a seasonal vertical ground-motion model using 20 years(1999-2019) of continuous observations from four GNSS stations mounted on bedrock sites. NEChina20, working together with the seasonal model, enables accurate and reliable ground and structural stability assessment in the Northeast.