The effect of heat treatment on the structure and magnetic properties of Sm-Fe alloys obtained by mechanical alloying was investigated. The crystallization temperature of Sm2Fe17, an amorphous alloy obtained by mechanical alloying, was determined using differential scanning calorimetry. Based on these results, various samples were annealed at different isothermal holding temperatures, and those with the best magnetic properties were found. Experimental studies show that decreasing the isothermal holding temperature from 750 °C to 630 °C increases magnetic characteristics nearly four times. The saturation magnetization, romance and coercivity of the Sm2Fe17 powder were 121 emu/g, 28.5 emu/g and 800 Oe, respectively.