The steady shear viscosity and dynamic moduli of low molecular weight polystyrene (PS) composites containing monodisperse crosslinked polymeric beads were measured with a cone and plate rheometer. Three different mixing temperatures were tried in preparing the polystyrene composites in melt state. At each temperature mixing was conducted at 50 rpm for the first 7.5 minutes followed by 100 rpm for another 7.5 minutes, with 0.2 weight % anti-oxodiant added. A sample melt-mixed at 175 ℃, the highest mixing temperature, showed a large agglomeration of polymeric beads, and the rheological properties with a yield stress. The yield stress was more pronounced with polar beads such as polymethyl methacrylate (PMMA) beads than with non-polar beads such as PS beads. On the other hand, a sample melt-mixed at 125 ℃, the lowest mixing temperature, produced the most uniform dispersion of polymeric beads, and exhibited the lowest rheological properties with no yield stress. A low molecular weight PS composite containing 20% of 0.2 ㎛ PS beads crosslinked with 5 mol% divinylbenzene (DVB) showed time dependent "aging" phenomenon at 180 ℃. We suggest that an affinity of a matrix and beads allowed movement of polymer chains and polymeric beads at elevated temperature, and as a consequence, PS beads have agglomerated, resulting in a large increase in rheological properties.