Abstract: The NS direction of tensometer of Zhangjiakou fixed-point deformation observation site has accelerated rising anomaly from June to December 2020. In view of this anomaly, we take Zhangjiakou fixed-point deformation observation site as the research area, based on sentinel-1 SAR descending imaging and small baseline subset (SBAS) technology for InSAR time series analysis. we obtains the vertical annual average deformation rate and deformation time series in this area from 2018 to 2020. The results show that the vertical relative movement rate of the surface on both sides of Zhangjiakou fault is less than 1 mm/a, and the fault activity is weak. Under the action of NNW-SSE tensile stress, the southern side surface of Zhangjiakou fault appears obvious subsidence movement relative to the northern side, this is the reason why the observation curves of the NS component of tensometer in Zhangjiakou seismic station showed the abnormal change of tensile acceleration trend.