The diagnosis relationship between isentropic potential vorticity conservation and baroclinic disturbance development has been used in forecasting cyclone development and understanding the dynamic fields of water vapor imagery. “Isentropic potential vorticity thinking” is based on isentropic thinking of isentropic analysis. This paper first reviews and discusses dynamic interpretation and operational application of isentropic physical fields according to the basic principles of atmospheric dynamics. The contents include isentropic surface distribution with height, vertical velocity in isentropic coordinates, moisture transport on isentropic surface, upper level fronts and jet stream characteristics on isentropic surface etc. Then, the physical fields and operational applicatoin on isentropic potential vorticity surface are discussed emphatically by comparing with physical fields on isentropic surface and quasi geostrophic vertical motion equation on baroclinic two layer model. The contents contain the definition of tropopause and its temperature, pressure and humidity distribution, fronts and jet stream characteristics on tropopause isentropic potential vorticity surface， vertical velocity on tropopause isentropic potential vorticity surface, cyclone development and potential vorticity in accordance with “isentropic potential vorticity thinking”, and how to improve numerical weather prediction model by using water vapor imagery etc.