Persistent agricultural irrigation makes loess terrace prone to landslide hazards. Therefore, it is necessary to identify and monitor the potential landslides with effective ways. In this paper, the time series interferometric synthetic aperture radar (InSAR) analysis technique is utilized to analyze both descending and ascending Sentinel-1 data stacks covering the period from January 2016 to August 2018. Active slopes on the Heifangtai terrace and surrounding area in northwest China are identified. Comparison between time series InSAR measurements and GPS measurements is carried out. Time series displacement analysis reveals that agricultural irrigation poses a great threat to the stability of slopes at the terrace edge. Meanwhile, temperature variation related displacements are also identified on bridges across the Yellow River with high correlation. Our study confirms the effectiveness of time series InSAR method, which can play a significant role in the identification and prevention of loess landslides.