Abstract. This paper considers basic approaches to modeling of economic cycles. Distinctions between common imbalances during economic development and economic crisis are examined. An approach to modeling of asymmetric cycles was proposed. This approach allows to determine cycle break points more accurately, and approximate the model closer to dynamics of real data. Influence of scientific and technical progress on behavior of economic cycles, their amplitude and duration was determined. If we provide analytical description for real investment flow and then distinguish aggregate effect of innovations on economy, we will be able to trace both the trend and corresponding cycle fluctuations. On the basis of US GDP statistical data for 1900-2014, approximated by modeling of the asymmetric cycle, there were defined characteristics of Kondratieff, Kuznets and Juglar cycles. These characteristics show themselves during cycle transformation in the form of cycle amplitude and duration changes. It is shown that transformation of economic cycles changes innovation content of mechanisms related to essential economic cycles.