A kind of ultrasonic transducer used in the nondestructive testing（NDT） of the spot welding is depicted.The special ultrasonic transducer has the characteristics of high-frequency

high-damping and narrow-pulse spot welding.Some improvements in terms of PVDF piezoelectric film and backing are carried out.The performance of the former and the latter transducers is compared

the comparison result indicates the affection of the relative factors to the characteristic of the transducer.The testing results to the transducers show that the performance of the transducer is good enough to be applied in the factual NDT of the spot welding.