Three different but interrelated phases of object-oriented methodology (OOM) in solving problems of electric power system network are discussed. The object-oriented analysis (OOA) phase of OOM focus on finding objects in the problem domain where objects can be found as naturally occurring entities or items in the domain of interest. Object-oriented design (OOD) for network topology processor (NTP) gives a flexible coding methodology and fast access to the database. The object-oriented programming (OOP) approach can be used in developing the power system analysis programs both for steady-state analysis and dynamic simulations.