Thin-walled aluminum has been widely used in the field of photovoltaic system. In order to guarantee the quality of thin wall aluminum, higher request is necessary for thin-walled aluminum on-line detection. Pulsed eddy current test was applied in thin-walled aluminum on-line detection. Signal was filtered and exported with high and low level of output voltage by the signal conditioning circuit. Then high level of output voltage was counted statistically to accomplish unqualified thin-walled aluminum hole detection.Finally unqualified products were picked out in time.This method can ensure the quality of thin wall aluminum.