On September 5,2022,a magnitude 6.8 earthquake occurred in Luding,Sichuan Province. In order to study the stress variation in the seismogenic zone of Luding earthquake,in this paper we selected three parameters,namely,b value,small earthquake modulation ratio and clustering rate,to calculate and study the regional seismicity prior to the Luding earthquake. The results are as follows. Before several strong earthquakes occurred in Luding and its surrounding areas,the regional seismicity had a long duration of low b value period,and the phenomenon of high clustering of small earthquakes and high modulation ratio appeared in the short term before earthquakes in the low b value state. The analysis of the seismic activity state of the Xianshuihe fault zone shows that before the Luding earthquake,the fault zone had a low b value state that lasted for nearly 10 months,and in the short term,the clustering rate increased and the modulation ratio increased. Through comparative analysis,it is believed that the Luding earthquake is the result of the tectonic movement of the Xianshuihe fault zone. The analysis shows that the temporal and spatial variation of b value,modulation ratio and clustering ratio of seismicity combined with the background of stress field is helpful to study the evolution process of large earthquakes.