The wear of aviation engine bearing parts is one of main factors that cause engine failure and serious accidents. The wear degree of bearing parts can be judged by monitoring the wear debris of the aero engine oil. In the past, the detection method has the problem of difficulty operation, high randomness and large quantitative error. This paper presents a method for the detection of aircraft engine wear debris based on electrical capacitance tomography (ECT) and establishes an experimental system and establishes a mathematical model of the relationship between the size or the situation of the abrasive particle and the change of capacitance value. Through the ANSYS and test experiment, the ECT method can detect the size of metal particles. The experiment system is equipped with 36 mm internal diameter sensors, which can detect the particles’ size of 3~8 mm.