A spherical polymerized toner with an average size around 10 mum and a span (D-0.9 - D-0.1)/D-0.5 of 1.5-2.0 is prepared directly by in situ suspension copolymerization of a mixture of styrene/ n-butyl acrylate/iron black. The particle size distribution (PSD) and morphological properties of the toner are investigated. On the basis of the analysis of droplet breakage, coalescence, and growth in the preparation of the polymerized toner, several factors affecting the droplet size, PSD, and morphology of the toner, i.e., agitation speed, ultrasonic introduction, and addition of different types and amounts of surfactants and pigment, are experimentally studied. Surface treatments of the pigment are conducted by modification with coupling agents and in situ prepolymerization. It is shown that surface modification of the pigment particles with coupling agents destroys the stabilization of the droplet, resulting in unexpectedly large particles. However, the in situ prepolymerization treatment is capable of maintaining the required PSD.