Based upon the reasonable calculatian of the some factors that can change the water level, the borehole data per hour during a period of 27 days in Yah zhou County, Shandong Province have been analysed by gradual regression method. The result was that influence of some factors on the water level has been better eliminated, and obtained the residual △(t) curves with random fluctuations, their mean error σ=6.97mm and complex correlation coefficient R=0.987. The mechanics process of the influence of some factors on the water level is preliminary discussed and some factors influence values are given Besides, by means of filtering analysis, the air-pressure data have been calculated, thus further understanding the assumption on air-pressure effect.