Mesocarbon microbeads (MCMB-1 and MCMB-2) were prepared by the thermal polymerization of medium coal tar pitch at the different atmosphere conditions. Primary quinoline insoluble (QI) was separated from medium coal tar pitch by extraction using the quinoline as the solvent. The distribution of diameter of QI and MCMBs were determined by Laser Particle Size Analyzer. FTIR combined with curve-fitted method, SEM and TEM have been used to study the difference of property and micro-morphology of QI and MCMBs. The thermo-stability has been characterized by TG/DTG analysis. The relationship between the content of ideal graphite carbon (I-g) and carbonization temperature of QI and MCMBs was researched by XRD analysis and curve-fitted method. The I-g and carbonization temperature of QI and MCMBs shows a good linear relationship.