Wudu and Tianshui strain stations have monitored the stress and strain near fractures and tectonic belts in southeastern Gansu since a few decades ago. As an effective observation method of earthquake precursors, it is of extremely vital significance and before many earthquakes it responded really well. The borehole strain gauge of pressure vessel style used in Wudu and Tianshui is the latest generation of strain gauge. In two or three months before the Minxian-Zhangxian M_s6.6 earthquake, the strain data in Wudu and Tianshui had shown varying degrees of abnormal changes. The NW orientation of two strain gauges appeared extremely obvious a-nomaly, which was similar to that in Wudu before two earthquakes which occurred in Min county in 20003 and 2004. They showed the same characteristics of precursory anomalies in three stages of,β₁,β₂ and γ₁.