Abstract: The concept of risk monitor as well as its expected function was introduced in the paper. Based on the requirement of risk monitor, a risk monitor system upon the browser/server structure was developed. Several practical applications were made to the system based on one specific risk monitor model. The result shows that this risk monitor system is able to successfully implement all the required functions and is competent for correctly reflecting the nuclear power plant risk, and can support the nuclear power plant staffs for their decision making.