We have established a stable North China reference frame,designated as NChina20,by using eight-year continuous observation data from 30 GNSS stations fixed on the North China active crustal block. NChina20 is aligned in scale with IGS14. The two coordinate systems are tied at epoch 2020.0. In this article we introduce the method of converting the positional time series with respect to IGS14 to NChina20. Applications of NChina20 in precise land subsidence and rebound monitoring are illustrated. The stability(accuracy)of NChina20 is 0.5mm/a in the horizontal directions and 0.6mm/a in the vertical direction. The stability of the reference frame degrades with the expansion of the coverage area and the time window. We recommend that the use of NChina20 is limited to the North China tectonic block within a time window of 20 years from 2006 to 2025. We have also developed a seasonal vertical ground motion model in North China using 20 years(2000～2019)of continuous observation data from 5 GNSS stations mounted on bedrock. The regional reference frame will be updated every few years to mitigate degradation with time and synchronize with the update of IGS reference frames.