The invention discloses a pulsed eddy current and electromagnetic ultrasonic composite based nondestructive body defect detecting method. Firstly, a permanent magnet is put on a round coil, an electromagnetic ultrasonic / pulsed eddy current composite probe is manufactured, a pulsed eddy current device is used for performing pulsed excitation on the probe, detecting signals are separated through a duplexer, filtered by a filter, acquired by a data acquisition system and analyzed, a separation and extraction algorithm is performed on mixed detecting signals in combination of developed strategies based on spectral analysis, filtering and the like, and composite signals are separated and extracted, so that eddy current detecting signals and ultrasonic detecting signals are extracted respectively from the mixed detecting signals and are used for detecting different types of defect information in different positions. The method for simultaneously separating and extracting the composite detecting signals has the advantages of high detection efficiency, wide detection range, compatibility for detection of both surface defects and deep defects, wider thickness detecting range and the like, and has a wider application prospect.