The relation between a black hole and a general blackbody system

Taking a black hole as a black body system, using generalblack body radiation theory, a Schwarzschild black hole and aKerr--Newman black hole are investigated respectively. It isconcluded that a black hole can be regarded as an ideal generalblack body system exactly for the changing process only. However, astationary global black hole cannot be smoothly regarded as a general blackbody system. A black hole has some special characteristics whichdifferent from a general thermodynamics system. This conclusion meansthat a black hole should be inherently dynamical, at least when it istaken as a black body system.