Bottom water coning is an important factor affecting reservoir development effect. Based on the theoretical investigation, numerical model of bottomwater reservoir is established. The accumulate oil production, water production and fluid production rate fromthe numerical simulation result were applied to calculate Yu Qitai water drive characteristic curve, and parameter b which can reflect water cut change in vertical wells was obtained. We used the response surface experimental design analysis method to study the effect of different factors on b value, and established the relation formula between the main influencing factor and b value. According toYu Qitai curve b chart, the regression curve and chart method for forecasting water cut change rule of vertical wells in bottom water reservoir was obtained. This chart
method was used in H12 well in an oilfield, the results prove the veracity. So this method is effective for forecasting water cut change rule of vertical wells in bottom water reservoir.