The crystal field (CF)- and external magnetic field- split ground state of Dy3+ in Dy3Al5O12 (DyAG) has been calculated based on the quantum theory in this paper. The eight CF-split levels are obtained, which are all twofold degenerates and are removed by the external magnetic field. On the basis of the results, the magnetic moments and the magnetic entropy changes of DyAG are calculated in the temperature range of 3THe3Ga5O12(GdGG) is stronger at low temperatures and dependent on the temperature and external magnetic field. Besides, the variation of the adiabatic temperature change ΔT with T is theoretically anticipated and the anticipated results are comparied with that of GdGG. It is found that the maximum adiabatic temperature change ΔT of DyAG is 1.27 times larger than that of GdGG when T=11 K and He=1 T. However, it changes to 1.15 times that of GdGG when T=16 K and He=2 T. There are differences between the refrigerative properties of DyAG and GdGG when they are in different external magnetic fields and different temperature regions. At low temperature s(THe is higher, GdGG is a good selection. This study is helpful to select suitable materials for the magnetic refrigeration technology.