The particle morphological properties of poly(vinyl chloride) produced by suspension polymerization in a pilot-scale reactor underdifferent reflux rates have been investigated. It was found that the monomer conversion decreased with increasing reflux rate. It was also observed that the cold plasticizer absorption (CPA) increased with reflux rate, whereas the bulk density (BD) and K value of the resin decreased. SEM micrographs showed that PVC resin with a rougher particle surface, more separate aggregates, and smaller primary particles was prepared at higher reflux rates. The particle size distribution determined by laser size analysis showed that the standard deviation of the particle size distribution and the mean particle size did not change significantly with reflux rate.