Abstract: Pure iron and Q235 steel were deformed using constrained groove pressing technology, and the effects of constrained groove pressing on microstructure and mechanical properties of the materials were studied. The results show that constrained groove pressing is an effective way of refining the grain size of pure iron and Q235 steel, and Q235 steel owns better refinement effect than pure iron. The strength and hardness of pure iron and Q235 increased after constrained groove pressing, but the elongation decreased, and the strength and hardness of Q235 steel were higher than those of pure iron, but the elongation of Q235 steel was lower than that of pure iron.