The data of radon and other items of deep well groundwater in Qing 6 well, Yumen city and Jing 3 well, Jingchuan county, Gansu province, are processed by multiple regression, correlation and univatent difference analysis to remove interference factor. The results show that there are obvious anomalies in data of both wells before Sunan M_S5.4, Tuolai M_S6.0 and Lixian M_S5.1 earthquakes. The reflecting and predicting earthquake ability are evaluated.