The propagation property of ultrasound on the bonded interface of si nt ered contact used in high voltage switch is investigated.It is found that scatte ring occurring on the interface is the main reason that causes the non-uniformit y of ultrasonic C-scan image of sintered contact.Based on the analysis

the morph ological filtering method for ultrasonic image is proposed.The experimental resu lt shows that the non-uniformity of ultrasonic C-scan image is corrected and the accuracy of nondestructive testing of sintered contact used in high voltage swi tch is improved by the morphological filtering method.