There are essential differences in the fractal characteristic parameters between the natural background and man-made targets, which provide a new kind of thought for target detection. The fractal application for the target detection is discussed. The fractal application always bases on the various fractal parameters, which sometime relies on fractal parameters completely, sometime combines the fractal parameters and other parameters each other, and sometime combines the fractal method and other methods each other. It is studied on the estimating methods of some fractal characteristic parameters and their application in the target detection.