Abstract: In the exiting risk monitor,the configuration information of specified plant is obtained by manual input.The historical running status and corresponding times of the devices cannot be put into risk monitor.In the Real-Time On-Line Risk Monitor（RORM） the running status and time of the components are collected and stored by automatic mode and manual mode.The historical running status and time from start to failure are considered in the cumulative failure probability of specified successive operating device.For example,two parallel pumps in a system experience the operation,hot reserve and then operation.The cumulative failure distribution functions of running failure basic event of two pumps are given.The functions show the instantaneous risk is related to the historical running status and time.The instantaneous risk curve shows an increasing trend with the time.