Abstract: Throughout studying the relationship between the compact density and the compacting pressure the compacting temperature, tasting the microhardness of particles in the compact, detecting the distribution oflubricant in the compact, the densification mechanism of warm compaction can be concluded as following:the compaction principle of iron powder is the same as that of conventional compaction. while the effective pressure during warm compaction is larger than that of conventional compaction. The temperature during compaction can slow down the progress of work hardness and improve the plasticity of iron powder. The lubricant is only effective at the optimum temperature. Under this condition, the lubrication takes place of viscous flow, which can be squeezed oat of the compact, effectively reducing the friction between particles and between particle and die wall, and also decreasing the ejection pressure.