In recent years,Virtual Instrument technology has been concerned in the arena of information technology and instrument manufacture.The authors propose the Virtual Instrument's concept,characteristics and configuration of both hardware and software.They apply Virtual Instrument to the humidity testing and brings forward the method to solute the problem,which traditional dry-humid balls humidity-testing instrument can not test several objects.By putting the emphasis on data acquisition,data processing,data storage and data display,the software design of virtual humidity test is discussed.