A three dimensional combination model has been put forward by means of adding an adjustment element under the fault in the combination model. The under adjustment element is composed of ductile material. It doesn't accumulate but transfers stress to the over accumulation element before earthquake,quits the boundless propagation of rupture by it's viscosity during earthquake,and controls the aftershock activity with dependence of it's deformation on time after earthquake.The acts of under adjustment element can be partly examined by creep curve of seismic fault.