Abstract: The determination of critical rate is a key issue of high-efficient development of bottom-water reservoirs, while in the Dupuit formula of bottom-water reservoirs' critical rate, it is unreasonable that the critical rate monotonously increase with the reduction of perforating level. In fact, checking the derivation process of Dupuit formula, there is an implied condition that the top of water cone just at the well bottom. However, it is found that it can't keep a stable water cone at well-bottom when producing with the critical rate computed by Dupuit formula. In the paper, a new computational method has been established without the assumption of water-cone top at well bottom. It assumes that it is a kind of radial flow at the upper and a kind of hemispherical flow at the lower around the well bottom. The example shows that the new method could optimize the perforating level and gain the critical water-cone height. The project case demonstrates that the method gained in this study is more correspond to reality.