To understand the co-seismic response characteristics of near-field water level and water temperature in strong earthquakes with magnitude less than 7, the Minxian-Zhangxian M_S6.6 earthquake was studied. The co-seismic response characteristics of digital water level and water temperature within 300 km of the epicenter were analyzed, and their associated relationship with the region where M_S4.0 earthquakes may occur was studied. Main analytical conclusions were as follows:co-seismic relative changes in amplitude in water level and water temperature induced by M_S<7.0 earthquakes were not large, and were of short duration during the last event, with sudden-jump being the main effect. Relative amplitudes of the co-seismic changes were not clearly different in different regions. Initial directions of the co-seismic changes were distributed in a four-quadrant form. The station concentration region where the initial direction was up was related to the region where M_S4.0 earthquakes may occur. Because the frequency of 6 < M_S < 6.9 earthquakes was relatively higher than that of M_S ≥ 7.0 earthquakes, and the scope of the near-field study was relatively small, the near-field earthquakes were found to be more advantageous than the far-field ones in predicting future earthquakes.