China has launched the first lunar satellite CE-1 on Oct. 24, 2007. A microwave sounder, named Chang'E Lunar microwave sounder (CELMS) was used to detect regolith information of the lunar surface. It is the first time that humankind directly applies sensed brightness temperature to investigate the lunar surface information by passive microwave sensor on lunar orbit. Therefore, it is necessary to set up theoretical models to describe lunar surface microwave transfer process, as well as heat conduction. These models will finally used for retrieving lunar surface information on regolith depths. In this paper, we generally describe the theory on lunar regolith microwave radiative transfer, analyse the factors influencing brightness temperature received by CELMS, including temperature profiles of the surface lunar layer, dielectric permittivity distribution, underlying rock reflectivity, as well as other thermal properties of the regolith. A primary solution on simulating lunar brightness temperature is given on basic knowledge of lunar surface, mostly derived from Apollo and Luna program. The further studies on lunar surface information reversion have been conducting by applying CELMS data and other information related.