The effect of cryogenic treatment on the mechanical and magnetic properties of WC–6% Co Ultrafine cemented carbides has been investigated in this paper. The results show that after the cryogenic treatment, the hardness slightly increases from 1750 to 1830, however, the transverse rupture strength decreases from 2510 MPa to 2480MPa. ,the magnetization decreased from 5.82% to 5.72%, decreasing 1.71%for 24 h, but the coercive force slightly increases and reaches the maximum of 24 kA/m for 2h.