The work is devoted to definition of sustainable development. Account is giving on base of a simple phenomenological model which operates such variables as resources and technologies on. The offering model is simpler and more obvious than Forrester's model as it seemed. The model enables to describe potential ways of world's development and make a choice between it. Problem of sustainable development treats as a problem of resources exhaustion. Solution of this problem possible by means of next ways: 1) resources economy, 2) renewal and revelation of it. In any case solution occurs due to technological expansion. Accounts shows that in both cases sustainable development is possible depending on conditions of necessary technological expansion and also it needs certain outlay.

Mathematical modelling in actual problems of science and technics