Mesocarbon　microbeads　(MCMB)　were　prepared　by　thermal　polymerization　of　medium-temperature　coal　tar　pitch　with　rosin　as　additive.　The　MCMB　were　characterized　by　FT-IR,　SEM　and　particle　size　analyzer,　and　effect　of　rosin　addition　on　the　preparation　of　MCMB　was　investigated　in　this　paper.　Results　show　that　rosin　can　be　used　to　efficiently　control　the　thermal　polymerization　of　coal　tar　pitch,　as　indicated　by　that　the　rosin　addition　is　benificial　for　promoting　the　nucleation　and　growth　of　MCMB　as　well　as　for　inhibiting　the　coalescence　of　MCMB.　The　MCMB,　which　possess　fine　sphericity　and　well　dispersity,　can　be　achieved　by　pyrolysis　of　the　modified　pitch　with　10wt%　rosin　at　450°C　for　2　h.　The　MCMB　obtained　have　a　mean　diameter　of　15.3　μm,　and　the　yield　of　MCMB　arrives　at　44.1%.