Abstract: The advantages and disadvantages of the measuration methods currently used of assimilation reaction between iron ore powder and CaO were indicated. The iron ore powder was first melted into liquid phase at the interface wetting CaO which led to the assimilation reaction that formed calcium ferrite. Discriminated methods of the parameters of the assimilation reaction such as starting and finishing temperatures were confirmed by Xray diffraction analysis. Upon this， the assimilation characteristic number taking the actual sintering temperature as the reference temperature was established. This assimilation characteristic number was a dimensionless number including kinds of important information during the assimilation reaction process， such as the heating rate， the assimilation reaction temperature and the assimilation reaction velocity， which overcame the shortcomings of the previous methods without considering the assimilation reaction process， and avoided using multiple parameters to characterize the assimilation reaction process.

Key words: iron ore powder, sintering, assimilation characteristic number, XRD, measuration