The WC-Co based cemented carbide has been widely used in engineering applications because of its remarkable properties high hardness, good toughness and excellent wear resistance. In the fabrication process, the powder preparation technique plays an important role in consolidating sintered compacts. In the present study, we investigate the effect of mechanical milling on the spark plasma sintering of WC-12Co cemented carbide. Two different powders of the WC-12Co, namely unmilled and milled powders, were prepared. The powder milling was carried out using a shaker mill under wet milling for 2 hours. Hereafter, the milled powder was dried at room temperature for 24 hours. The powders were then densifiied using Dr. Sinter SPS 625 under vacuum conditions below 10 Pa, compaction pressure of 40 MPa, and a heating rate of 100 ℃/min (0-600 ℃) and 20 ℃/min (600-1150 ℃). The results indicate that the powder milling affects the crystallite size, sintering behavior, and hardness of WC-12Co. The crystallite size of WC-12Co powder is reduced from 68.8 nm to 32.1 nm after milling. This results in a slight decrease in sintering temperature and an increase in the density and hardness of the sintered alloy. The further comparative results are intensively discussed in this paper. © 2025 Institute of Physics Publishing. All rights reserved.