Formation, structure and magnetic properties of Ｓｍ2Ｆｅ17-xＭxＣ1.5（Ｍ＝Ｇａ，Ｓｉ） compounds prepared by arc-melting were studied. The Ｓｍ2Ｆｅ17-xGaxＣ1.5(3≤x≤6) carbides crystallize in the rhombohedral Ｔｈ2Ｚｎ17-type structure and the single-phase compund of Ｓｍ2Ｆｅ17-xSixＣ1.5 can only be obtained as x is 2. It is found that the Curie temperature of Ｓｍ2Ｆｅ17-xGaxＣ1.5 compounds decreases monotonically with increasing Ga concentration x from 633K for x=2 to 351K for x=6，and the Tc of Ｓｍ2Ｆｅ15Si2Ｃ1.5 compound is 578K. All compounds studied in this work exhibit an easy c-axis anisotropy at room temperature. The anisotropy field of Ｓｍ2Ｆｅ14Ga3Ｃ1.5 and Ｓｍ2Ｆｅ15Si2Ｃ1.5 compounds is found td be 90 and 115 kOe, respectively. A room-temperature coercivity of 16 kOe is obtained in rapidly quenched Ｓｍ2Ｆｅ15Si2Ｃ1.5 alloy prepared at。speed of 25 m/s.