Abstract: Polycrystalline samples of La_0.64Ca_0.28Sr_0.02MnO₃ with deficient in La³⁺-site were prepared by the sol-gel technique.the large magnetic entropy change of the sample is analyzed foom the point of view of the structure,the magnetization curve,the magnetic phase transition,ect.The maximum magnetic entropy change,3.01 J /(kg·K),is obtained at its Curie temperature(264 K) under the field of 1 T for x = 0.06 sample.With large magnetic entropy change at room temperature under the low magnetic field,room-temperature refrigeration.