The effect of vacuum cyclic heat-treatment based on spark plasma sintering (SPS) technique on the microstructure, composition and properties of as-sintered 93W-4.9Ni-2.1Fe tungsten heavy alloy has been studied by optical microscope, SEM, EDS and three-point bending tests. The results show that the matrix penetration into W-W grain boundaries enhances significantly, and the W-W contiguity and dihedral angle decrease gradually with the cycle index increasing. SPS cyclic heat-treatment does not obviously change the micro-hardness and grain size. The matrix is strengthened by the increasing content of tungsten owing to the treatment. The bending strength of the alloy increases significantly after 2 cycles. When the cycles goes up to 20, the average bending strength reaches 2321MPa, which is 160MPa higher than that of the conventional liquid-sintered and solution-treated 93W-4.9Ni-2.1Fe alloy. The microstructure and properties of 93W-4.9Ni-2.1Fe tungsten heavy alloy can be improved apparently by SPS cyclic heat-treatment.