A 16-electrode electrical impedance imaging system was designed to facilitate the detection of defects in the aircraft skin structure and to make up for the lack of manual testing. The sinusoidal signal was used to stimulate the sample in a relative excitation mode. Compared with the relative reference amplitude obtained by forward operation, measured value demodulation information and the image reconstruction algorithm were used to obtain the conductivity distribution image of the skin structure based on open source software Octave and package EIDORS. So the defect status of skinning structure is characterized by the changing trend of its conductivity. Commonly used material 2024 T-3 aluminum alloy plate in aviation manufacturing industry was selected as a sample for real-time resistance anti-imaging experiments, and the reconstruction image quality is evaluated by PE and other evaluation indicators. The results show that the change of conductivity caused by defect of the sample can be measured by using the system and the system can effectively monitor the structural defects of the metal skin.