The load/unload response ratio(LURR)is a method to explore the evolution of regional stress field by detecting the difference of responses during the loading and unloading induced by tidal stress. Taking M_S6.0 Changning earthquake as a case study,we analyzed the evolution of LURR time series,the change of stress state of source media,and the possible pre-earthquake anomaly. Firstly,the Benioff strain of small earthquakes are adopted as the loading/unloading response,and the change of Coulomb failure stress induced by earth tide,in the tectonically preferred slip direction on the fault surface of main shock,is used for differentiating the loading and unloading periods. The results show that the LURR values have anomalous increased since the beginning of 2018 and reached the peak in mid-2018. Meanwhile,the LURR method is also applied to the groundwater level data in the near field wells,and the pre-earthquake anomalies are observed too. In addition,we find that the changes can also be supported by the variations of the geodetic time series observed in the same neighborhoods during the same periods. Obvious changes in the EW and NS components of SF horizontal pendulum tiltmeter are observed during the period of LURR anomalies,which indicate that significant anomalies could be observed in LURR time series produced using both seismicity and groundwater level change as data input,suggesting the high stress accumulation in source media.