Poisson curve is a accurate method of settlement prediction, but it is used in condition of equal interval data, which is hard to carry out in actual engineering.

Based on the consolidation theory of ground with vertical drains under the condition of equal vertical strain, approximate theory settlement curve calculation method is put forward.

In this paper, the writer proposed a method of equal pile point settlement for calculating P-S curve of pile. The result of calculation are fairly checked with those measured in the field.