According to the principle of flow equivalence and the method of resistance coefficient,a practical simplification method of “replacing well with surface hole” is proposed.This method simplifies three-dimensional pressure-reducing wells as two-dimensional surface holes at the same position,and the calculation formula of surface hole radius is given in this paper.It is proved that the method has a promising application in terms of row wells and group wells.Based on the project of double line lock chamber,the calculation accuracy of the practical simplification method is evaluated by the comparative analysis of seepage potential distribution,seepage flow distribution and lifting pressure variation.The results show that the simplified method can effectively reduce the number of model elements and nodes,and greatly save computing resources in numerical simulations (FEM).Moreover,the outcomes illustrate that the seepage potential and the lateral distribution of discharge flow of equivalent surface hole is the same as those of relief well,and the top lines of each part in those two models are almost overlapped.The relative error between the total discharge flow of equivalent model and the right line of original model is only 1.7%,the relative error of the average uplift pressure is 5.4%.It is suggested that the equivalent orifice rate should not be less than 10%,the seepage analysis can be carried out directly according to the fully permeable of the lock chamber when the equivalent orifice rate is greater than 50% owing to the fact that the lifting pressure is basically equivalent to the situation of complete permeability.