Abstract: The effect of heat-treatment at different temperatures (700 ℃ and 900 ℃)on damping capacity of the Ni49Ga27Fe21Co3 ferromagnetic shape memory alloy (FSMA)was investigated by using low frequency torsion pendulum.The results show that when the strain amplitude was less than 5.0×10-5the damping capacity of the as-casted alloy was determined by frequency.Solid solution of (Fe,Ni)in the alloy decomposed and new phases precipitated during the heat-treatment.The damping capacity of the heat-treated Ni49Ga27Fe21Co3 alloy was determined by frequency and was superior to that of the as-casted alloy and the maximum value was 0.023.