A computer system for on-line chemistry monitoring system located in secondary side of PWR plant is under developing. Keithley 500A Mainframe and AMM1A and AIM3A modules are used for data acquisition and scientific and engineering software package of ASYST is used for developing software program. The contents are as follows; (1) Data Acquisition and Real-Time Display. The output signals of monitoring chemical sensors are stored in PC showing real-time data display as true values and graphics. (2) Data Management and Trending Graphs. The data stored in PC are outcoming in various graphic mode for data management such as simple trending graphs screen display, time duration plot and histogram plot. (3) Daily Basis Data Manual Input. The chemical analysis data of grab sample are stored in PC by manual input for supplemental data. (4) Tabular Data Report Preparation. Summarized daily, weekly, monthly, quarterly and yearly reports are prepared with various mode of graphic display. (Author).