In no description of power line channel models with time varying and frequency selecting characteristics available has any account been taken of the channel effect of energy time frequency distribution（ETFD）. The classification of power line channel effects into the multiplicative and additive ETFD is proposed， which compares their differences by using three time frequency analytical methods and simulates the available slot number in every sub-carrier or the available sub-carrier number in every slot using smooth pseudo Wigner-Ville distribution（WVD）. The three energy assignment methods of average or greed or cellar are also recommended， which simulates their energy time frequency assignments in the given channel effect and attainable total energy. The results obtained show that the average algorithm has the lowest operational complexity and the cellar algorithm the lowest energy loss values.