Great earthquakes often occur along or near active fault belts. Thus,monitoring and research on fault deformation are quite important. Methods such as short-leveling,shortbaseline and integrated monitoring profile across fault belts have been used to monitor fault activities for many years. GNSS observations are mainly used to obtain the horizontal velocity field in large areas and to study the activities and deformation of major blocks.GNSS technology has been used to monitor and study the deformation of faults from a different aspects. In this paper,some applications and new explorations of GNSS are discussed. They are:( 1) Research and monitoring of strike-slip activities of faults with GNSS.( 2) Research and monitoring of vertical activities of faults with GNSS.( 3)Investigating the laws of deformation of blocks on the sides of fault zone and setting up strain models to deduce the activities and deformation of faults with respective models and compare the deduced results with the actual measurements across fault. It is concluded that a larger discrepancy between the deduced and the observed deformation indicates a stronger interaction between the blocks,which can be important for predicting the location of a strong earthquake and assessing seismic hazard,as well as the seismicity trend. Thus, monitoring and research on fault deformation are quite important. Methods such as short-leveling, shortbaseline and integrated monitoring profile across fault belts have been used to monitor fault activities for many years. GNSS observations are mainly used to obtain the horizontal velocity field in large areas and to study the activities and deformation of major blocks. GNSS technology has been used to monitor and study the deformation of faults from a different aspects. In this paper, some applications and new explorations of GNSS are discussed. They are: (1) Research and monitoring of strike-slip activities of faults with GNSS. (2) Research and monitoring of vertical activities of faults with GNSS. (3) Investigating the laws of deformation of blocks on the sides of fault zone and setting up strain models to deduce the activities and deformation of faults with respective models and compare the deduced results with the a ctual measurements across fault. It is that a larger discrepancy between the deduced and the observed deformation indicates a stronger interaction between the blocks, which can be important for predicting the location of a strong earthquake and assessing seismic hazard, as well as the seismicity trend .