In this paper, we introduced the technique of GPIB bus interface. Through the controlling of the GPIB interface board, the computer controlled the current source and the voltmeter, both of which have GPIB bus interface, and a virtual instrument testing system for I~V curve was composed. The virtual instrument front panel and the background graphical control program in Labview environment accomplish virtual instrument testing task along with the hardware system. Keywords: GPIB;Labview;Virtual Instrument