According to the single battery's series structure in the fuel cell stack, we develop an on-line fuel cell voltage monitoring system, and realize VISA library functions’ call and operation data acquisition and storage successfully in the Delphi development environment. It’s introduced mainly that the monitoring principle, hardware structure, software design and the main feature. The actual application proves that this system has realized high-precision and real-time monitoring of the output voltage of the fuel cell for multi-channel, and has multi-condition operation by setting original parameters easily, thereby, the system has more applicability and well reliability.