Abstract In order to overcome disadvantages of the single-chip based humidity test system, a humidity monitoring system was designed using virtual instrument technology. The system consists of data acquisition module, signal process and display module, super-threshold alarm module, data storage and historical data recall module, and help module. A combination of humidity and temperature sensor was adopted to obtain environmental humidity and temperature information, and a PCI bus based data acquisition card was used to achieve the function of data acquisition, the purpose of detecting temperature is to compensate the influence of temperature changing on humidity data. The software was developed by LabVIEW. The block diagram of the software was showed, methods of implementation in signal acquisition, scale conversion, temperature compensation, noise filtering, super-threshold alarm, data storage, recall of historical data, and display of humidity monitoring signal were also expatiated. By this system, environmental humidity change information can be real-time obtained, and can be displayed on monitoring screen. At the same time, the system has abilities of data storage, historical data recall, and super-threshold alarm. The whole system is compact; the interface is friendly, and easy to operate.