A novel rapid search strategy with a long focusing range was proposed,which improved the efficiency of mountain climbing servo(MCS).The long-range coarse focusing was gotten by using linear interpolation according to Variance function.Gauss interpolation realized the fine focusing nearby the peak of focusing curve based on the gradient energy function.The experimental results demonstrated that this algorithm can focus quickly in a long-range with high focusing accuracy,and the same conclusion can be gotten for the different images.The algorithm applied successfully to the focusing system of micro-electronics visual measurement.