The purpose of this research is to discuss the changes of pressure, temperature, mass and energy varying with time of the fire scenarios. Setting up models for the evaluation of parameters important in fire scenarios and using the Guide User Interface (GUI) in the GUI Toolbox of Matlab to execute these models, the analyzers can easily use the methodology established in this paper for the studies of fires in the enclosure. Based on a variety of fire-related correlations obtained from test data, this study built up the corresponding GUI and performed the case studies with fire loads, vent areas, and the temperature and mass flow rate of smoke as four key variables. The results obtained from these case studies appear to be reasonable. In the future, it is expected that more experimental data can be obtained to compare with the evaluations resulting from analytical simulations; therefore, the computer simulation can be made more practical.