In order to reveal the influence of working medium parameters upon economic behavior and environmental indices of the powergenerating unit

and to discuss the technical and economical basis for developing supercritical units in our country

the coal consumption rate of powergeneration（g/kWh）

pollutant emission rate of SO2 and CO2 （g/KWh） of supercritical

subcritical （imported）

superhigh pressure

high presurre

and medium pressure powergenerating units

which are operating in China at present

have been calculated by using unit consumption theory and exergy analysis method; the technical and economical evaluation for supercritical and subcritical units have been carried out from aspects

such as coal consumption rate of powergeneration

emission rate of pollutants

and construction cost per kW

by using stratification analysis method of the comprehensive evaluation theory. Results show that the energetic development of supercritical units claims localization to be realized as quickly as possible to reduce unit construction cost on the one hand

and guiding function to be strengthened for environmental protection policy （or marketoriented mecbanism） on the other hand.