从热力学唯象理论出发，讨论了Ⅱ类超导体在绝热加磁场的制冷效应。Ⅱ类超导体从 Ｍｅｉｓｓｎｅｒ态到混和态， 从混和态到正常态的相变都是二级相变， 无制冷效应。讨论了Ⅱ类超导体在 Ｍｅｉｓｓｎｅｒ态和混合态区域的制冷效应， 从物态方程出发给出了低场和高场的降温方程。 Based on the phenomenological theory of thermodynamics, the cooling effect of class Ⅱ superconductors on adiabatic and magnetic fields is discussed. Type II superconductors from the Meissner state to the mixed state, the transition from the mixed state to the normal state are secondary phase transitions, no cooling effect. The cooling effect of the superconductors of type II in the Meissner and mixed regions is discussed. The cooling equations of low and high fields are given from the equation of state.