Extensometer at Xiaoxinzhuang cave is disturbed seriously by pumping. Strain data and ground water-level at Sangzi show synchronous change in the pumping season. In this paper，the variations of water-level and strain at the two directions are calculated from 2004 to 2013. Regression models between water-level and strain variations at the two directions are built using the linear least square method. One model meets the t test with α＝0.05 and the other is α＝0.01. Therefore，the confidence level values are 95% and 90%. Corresponding estimator and prediction interval of stain at the two directions are calculated according to water-level variations in 2014 using the model. On account of that stain measured value is in the prediction interval，the accelerated change of stain at the two directions from mid-March,2014 is correlated with pumping with lower confidence as seismic precursor anomaly. The result indicates that it is possible to calculate the stain variations of Xiaoxinzhuang for pumping using water-level data of Sangzi and helpful to determine the anomaly confidence of stain accelerated change at pumping time.