In this paper, by describing several types of interface widely used in computer testing system, we point out the disadvantages of traditional interface. Then we give a solution to implement data transfer between computer and periphery hardware by using USB interface that is very popular now. Furthermore, some different designs of USB interface are presented. Also we give an analysis about them. Subsequently we analyze the distinct characteristics of a real system and give a USB interface application to computer testing of PCB (Printed Circuit Board). And then, we present a hardware structure of the USB interface and its function analysis. Moreover, we introduce the supporting software, which include USB device driver, USB firmware and system application software.