In this paper, a new approach for model-based monitoring of turbine heat rate is developed, where the superheat steam flow is calculated according to the output power of the turbine generation instead of the flow of feed water. A regenerative system model is built based on the operating state and historical data to predict the parameter values in the heat rate calculation. The results of the model calculation also verify the turbine operating parameters that are measured on site. The new approach in this paper was applied in a 660 MW generation unit. The monitoring results of this approach are more stable and accurate than traditional monitoring results.