Abstract: Mercury injection apparatus， which is a measuring instrument for solid porosity and pore size distribution， is widely used in the analysis of powder metallurgy and ceramic materials due to its advantages such as high precision and easy to operate. Based on mercury injection method， the oxideconsolidation index (OCI) is defined to represent the consolidation degree in process of roasting for pellets. The OCI was calculated according to measuring porosity and pore size of different iron ore pellets when the green pellets were roasted to product pellets. At the same time， the compressive strength of these product pellets was detected. Comparing OCI and compressive strength of pellets， it is found that， when the pelletizing technique and raw materials are stable， the oxideconsolidation index (OCI) is higher， the consolidation degree is more complete， and the compressive strength of product pellets is higher. This method not only exposits the physical character of pellets， but also represents the consolidation degree of pellets precisely， which will provide an analysis method and evaluating indicator for pellets to investigator and producer.

Key words: mercury injection method, iron ore pellet, oxideconsolidation index(OCI), porosity, strength