Abstract: The elevation error of seeker tracking low altitude target was affected by multipath propagation. The traditional ‘little plane’,which calculates diffuse reflection coefficients, was used in uniform terrain meshing. But uniformterrain meshing has a high error rate in big grazing angle. An improved method which doesn't divide terrain uniformly and analyses effects of four paths propagation was proposed. The method of estimation elevation estimation commonly is open-loop track. A close-loop tracking method and improved method of‘little plane’which calculates diffuse reflection on ground/sea were presented. When the seeker track low altitude target, the elevation error was simulated better and calculation time was greatly reduced.