Terrain following allows an aircraft to maintain a relatively constant height above the ground. In order to follow the terrain, a terrain following radar can measure the relative position of the terrain mainly generated by digital elevation models(DEM) for simulation. The closest point between the aircraft and the terrain cannot be obtained analytically because of high non-linearity of the DEM. Accordingly, a method of finding the intersection point between a line dividing the range of the azimuth and elevation angle at equal intervals and the DEM is widely used. However, densely dividing the intervals for better performance results in high computation loads. To address this, we propose an accelerated algorithm suitable for terrain following radar. It considers all DEM data in the search area to get rid of unmeasured areas, and reduces the computation load through a simplified method of distinguishing whether or not it is blocked by terrain. In the simulation, the proposed methods demonstrate reduced computation time compared to the traditional methods with comparable performance in terms of the number of the undetected range gate.