The progress in theoretical modeling of microwave remote sensing in recent years is briefly reviewed in this paper. As the models for the objects of remote sensing the theories and numerical approaches of electromagnetic scattering and thermal emission of random discrete scatterers

continuous random media

and randomly rough surface are discussed. The applications in both active and passive remote sensing of the earth terrain

vegetation canopy

soil

snow and ice

atmospheric cloud and rain

sea ice

and sea surface driven by wind

etc. are also introduced. With the future development of the remote sensing technology

further efforts to develop more accurate models and quantitative mathematical physical approaches for remote sensing of the nature

and to develop numerical data analysis and parameter retrieval must be done. Some comments on the research progress in theoretical modeling of remote sensing are discussed

and several interesting and important topics for future research are pointed out.