The invention discloses a method for establishing a multi-scale pressure field. The method for establishing the multi-scale pressure field includes the steps that a large-scale pressure field shown in the specification and a medium-and-small-scale pressure field shown in the specification are acquired according to three-dimensional seismic data and logging data; the large-scale pressure field shown in the specification and the medium-and-small-scale pressure field shown in the specification are overlapped, and then the multi-scale pressure field P is acquired. The medium and small pressure field is added, the brand-new multi-scale pressure field is formed, and the accuracy of the pressure field can be improved.