This thesis represent the study of system modelling by Matlab for designing separator model with varies sub-systems and simulation. The designing process of separator require calculation of some factor that effect the height and diameter of the separator. Constraint such as terminal velocity of vapour inside the separator be part of the cause in deciding the parameters of the separator. Therefore, each of the constrain is converted into block function in Matlab to create modelling system that are more efficient to optimize the usage time and cost. Besides, this thesis also intends to develop a sophisticated file management system for separator incorporated with applicability of simulation tool. The approcah such as component referencing and block library was also applied in order to optimize the effectiveness of modelling using Matlab. Creating a block library for modelling as proposed may reduxe time for designing process as some of the component and function are similar for different model. In addition, isers are easy to keep track of each function and file as the specific library is created for needed function.