The user interface is the direct mediator between the user and the system. It is one of main factors which influences how fluently and with what time resources system could be integrated into business process and how fast systems deployment could be performed. User interface is one of the most important points in software design, because it determines quality and rate of project implementation. Software design methodologies, based on Unified Modeling Language (UML), Oracle CASE, introduced by C. Finkelstein, D. J. Anderson, V. Balasubramanian, A. Granlund, D. Lafreniere, D. Carr are analyzed in this paper. The user interface modeling method based on data flow specification is presented in this work; the software prototype of modeling user interface based on this method is implemented.