Based on the experimental isothermal entropy change of the magnetic materials Gd x Dy 1−x , the thermodynamic performance of a regeneration Ericsson refrigeration cycle is evaluated and analyzed. The effects of non-perfect regeneration on the cyclic performance are highlighted. For a room temperature hot reservoir, the cooling quantity, non-perfect regeneration heat quantity, and net cooling quantity of the established regeneration Ericsson refrigeration cycle are calculated as a function of the cold reservoir temperature. Furthermore, for several typical compositions x of the Gd x Dy 1−x alloys, the values of the cooling quantity, non-perfect regeneration heat quantity, work input, net cooling quantity, and coefficient of performance (COP) are listed for given temperatures of the cold reservoir. The cyclic performance of the Gd x Dy 1−x alloys with different composition x is compared and some significant analyses are provided.