A novel CVD method of preparing ultrafine rhenium powders was investigated in this paper. The Re2O7 gas obtained by decomposing NH4ReO7 was transported to the reduction chamber and then reduced by H2 to form rhenium powders. In order to evaluate the effects of sintering on properties of rhenium particles, such as crystal size, morphology, surface conditions and particle size, the samples of rhenium powders prepared at different reduction temperatures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experimental results show that the sintering effect among particles is enhanced with increasing of reduction temperature, resulting in larger crystal size, smoother surface and larger average particle size of the rhenium powder.