Hostile and complex environment causes the subsurface corrosion for inservice aviation structures, posing a severe threat to the structural integrity. As for the integration of pulsed eddy current testing with uniform excitation yields Gradientfield Pulsed Eddy Current testing(GPEC), the gradientfield pulsed eddy current testing has reflected its advantages in detection and evaluation of corrosion in conductive structures. This paper focuses on experimental investigation of GPEC further. Aimed at the problems that the imaging information of subsurface corrosion obtained in aviation structures is not abundant, the paper further proposes the relevant imaging processing along with a new image feature proposed. The proposed imaging processing method is further discussed regarding superiority in subsurface corrosion visualization. The results show that the image feature extracted from the postprocessing images has the linear correlation with the corrosion depth, which, in conjunction with acquired corrosion images, and benefits the quantitative evaluation of subsurface corrosion in aviation structures.