The effective business management should be provided by an appropriate management system which is based on the enterprise architecture. The latter provides the achievement of the strategic goals of a company by means of business processes and projects. Many representatives of the community emphasise society confess a great role of working with changes using a project approach. However, there is still no consensus about the place of project management system within the enterprise architecture. The model of enterprise architecture developed in the paper defines the place of project management within the enterprise architecture. This paper aims to develop an approach to the enterprise business-architecture formation and to propose the means of modeling its all business components.