Abstract: A new excitement source of eddy current testing was presented to use an arbitrary waveform as the development of the eddy current testing. A direct digital synthesis(DDS) technology, based on large capacity synchronous dynamic random access memory(SDRAM), was used, in which the table of arbitrary waveform amplitude generated by CPU according to testing requirement was stored, and FPGA outputs the amplitudes to D/A converter. The output, after being filtered using low pass filter and power amplification, drived the eddy current probe. It was showed that the new method was able to resolve various complicated computations when the resources were limited so as to use DDS, and the presented arbitrary waveform excitement system that was stable and flexible could satisfy eddy current testing requirements at present and in the near future.