Pulsed infrared thermography uses the pulsed heat source which has a plurality of frequencies,but lock-in infrared thermography uses the periodic heat source which has only a single frequency.Since the work-style of heat source and data processing method are different between these two technologies,the article uses the two above mentioned technologies to inspect the PCB and Back-drilled flat bottom holes sample,according to the result of two technologies,differences between the two technologies and their advantages and disadvantages are presented.