The invention relates to an interface assistant spinneret-free electrofluid mechanics method, in particular to a method for applying a force to a spinneret-free electrofluid mechanics interface namely a starting jet flow interface of a charged and processed material so as to assist the charge fluid to break through the surface tension of the electrofluid mechanics interface and the mutual acting forces in the fluid to process and deal with a processed material, in addition to an electrostatic force, and a selectable acting force, of which the vertical magnetic field acts on a sharp needle-shaped bulge vertical to a surface layer and formed by the perturbation effect on the free surface of a magnetic fluid, which adapts to the charged fluid motion direction namely a direction that the direction of an acting force is the same as that of an electric jet flow or has the same direction component. The method suitable to serve as the method for preparing a superfine material which has one or more functions including separation, protection, antibacterium, deodorization, catalysis, sensing, decoration, structure supporting, biocompatibility, storage, controllable release, electric conduction, restoration, medical treatment, health care, intelligent response, redolence and adhesion. The prepared superfine material is applied to structures of solid, hollow or nuclear shell structured particles, fibers, thin films, cloth blocks or block structures, and can be processed with low cost on a large scale.