Aiming to meet demand of the multi-channel and high-speed eddy current testing equipment used in current industrial production line, a multichannel online eddy current testing system is designed. The testing system is composed of eddy current signal processing circuit, multi-channel data acquisition system, real-time control computer based on Vxworks operating system, data management computer and relative software. The excitation frequency of eddy current signal processing circuit varies from 300 Hz to 3 MHz. The range of adjustable sensitivity is 0 ~ 72 dB. With 200 K sample rate for every channel, multi-channel data acquisition system can acquire the data from four eddy current signal channel simultaneously, which is able to work on the 1 200 m/ min production line with through-type eddy current probe. Transferred through PC104 bus to real-time computer, the data is identified and labeled by procedure. The data management computer displays the impedance plane according to the data. To adapt to different testing condition, it is also responsible for the parameter adjustment. In thin-wall copper pipe testing experiment, the testing system shows multi-channel data acquisition ability, high SNR and good effect for 0. 6 mm minor defect testing.