Among numerous electromagnetic interference sources, electrical fast transient (EFT) has become one of the major threats to the electromagnetic compatibility (EMC) of IC. In this paper, two different EFT generators connected to a uniform IC level test platform are used as interference sources, and asynchronous injection method is adopted to perform the EFT injection test of microcontroller. According to the results of test, it is found that power supply network has worse immunity to standard EFT pulse.