High frequency transformer is one of the most important components in the switching converter. By testing magnetic components under various operating conditions, we can avoid the overheating cores which may cause failure of the whole system. With cooperating the arbitrary function generator of Tektronix AFG3022B and the ArbExpress software, the paper mainly studies three methods: direct method of waveform generation, the method of waveform math and the method of equation editor. Combining the power amplifier, oscilloscope and other test instruments, we can effectively imitate the core excitation waveforms such like square wave, rectangular wave, symmetric wave and other typical waveforms. At last, the experimental results show its availability.