As a part of the improvement in liquefaction techniques of waste expanded polystyrene (EPS), the pyrolysis of EPS with alpha-methylstyrene (MSM) or 2,4-diphenyl-4-methyl-1-pentene (MSD) as a chain-transfer agent was studied at a temperature of about 200 degreesC. Eight kinds of spherical fillers with different material or size were each loaded in the reaction system and the synergistic effect of the spherical fillers and additives was investigated. The molar ratio of MSM or MSD to EPS decreased when the scale of EPS increased from 2.5 g to 5 g, but the absolute weight did not change. The efficiency of heat-transmission was improved by loading of the fillers. When the stainless fillers were loaded in the system of the MSM additive, the molecular weight of EPS lowered with an increase in the total surface area of the fillers. But this tendency was not found in the system of the MSD additive because of the high viscosity of the system.