Abstract: Using borescope equipment to inspect the inside of turbofan engines is an important technology to the daily fault diagnostic of aeronautic engine. In all the aeronautic engine interior faults, vane′s face fault is a regular one. Towards vane′s face fault, a kind of fault detection and estimation method was presented. First, vane′s face fault was detected by the SUSAN(smallest univalue segment assimilating nucleus) edge detector. Second, the image was analyzed by wavelet transforms to achieve the different frequency components at different locations. Third, the energy of the alternating components around fault was computed by the spectrum. And at last the vane′s face fault was detected and estimated by the energy. Test result shows that this method can quantificationally detect the fault of aeronautic engine vanes and estimate the grade of the fault. It provides a scientific basis for the fault detection and estimation of aeronautic engine vanes by borescope.