Abstract: The brickwallmodelwas used to directly calculate the Boson entropy of scalar field in the background of1+1 dimensional(space-time) black holes. The results show that the entropy is related to both the outer and innerhorizons. If the contribution of the innerhorizon is considered, the entropy approaches zero as the radiation temperature approaches zero. The entropy satisfies the Nernst theorem, so itcan be regarded asPlank absolute entropy. If the contribution of the innerhorizon isnot considered, the entropy has a logarithmically divergent term, which is the same with the known conclusion.