In this study, a computer simulation model for library CD-ROM LAN systems was created. Using this model, the system optimization problems were examined. The simulation model imitated the process of the actual decision variables changing their values and generated the corresponding results. Under a certain system environment, if the values of decision variables are changing, the system performances are getting changed also. This study investigated these relationships with the created model. The system users' interarrival time, service time, and other relevant data were collected on randomly selected days in a university library. For data collection, both of the observation and the system automatic metering software were used. According to the collected data, a discrete events simulation model was created with GPSS/H. The simulation model was proven valid and accurate by a pilot test and by the calculation with queuing theory. Statistical tests were used for data comparison and analysis. In addition, animation technique was used to show the simulation process by using Proof Animation. By this technique, the simulation process was monitored on the screen.