This paper explains the methodology of the system approach in the spatial planning process. Spatial planning is a tool for implementing sustainable development of the territories. Spatial planning deals with a set of territorial issues that are considered as a system with dynamically changeable elements both in time and space. This methodology can be used on national, regional and local levels as well as in different forecasting periods of time – long-term, medium and short-term. The results of spatial planning proposals should be multivariate, objectively evaluated and used for timely decision-making. That is why the planning process should be formalized using modern methods of modeling. Forecasting proposals are made based on the results of comparison of economic and territory development scenarios on different temporal scales, taking into account the requirements for environment protection, land use and the possibilities of social-economic development. Scenarios should be developed in accordance with the purposes and economic opportunities of public policy for each forecasting period. Changes should be seen in terms of the values and sets of indicators of sustainable development. The interconnections of the parts of the process and their diverse planning terms, as well as feedbacks and place of dynamic modeling are shown in the frame of spatial planning process. Spatial planning is a continuous process, which reflects the development of society and national economy, and its study has all aspects of a system approach.