Epoxy resin (Ep850) / acrylic composite latex was prepared by a miniemulsion polymerisation method. The effects of preparation conditions, such as homogenization time and amount of anionic or nonionic emulsifiers and costabilizer, on droplet size of the monomer miniemulsion were investigated. The longer the homogenization time and the larger the amounts of emulsifiers, the smaller the droplet size of the monomer-miniemulsion became. If the homogenization time was long enough, the amounts of emulsifiers correlated to the droplet size of miniemulsion. The larger the amount of costabilizer, the better the stability of monomer-miniemulsion became. The effects of droplet size of the monomer-miniemulsion on properties of the obtained latex, such as particle size of the latex, solvent resistance of its films and solubility in tetrahydrofuran (THF), were also investigated. When the droplet size of the monomer-miniemulsion was large, the particle size of the obtained latex was smaller than the droplet size of monomer miniemulsion. On the other hand, when the droplet size was relatively small, the particle size of the obtained latex was almost the same as the droplet size. Comparing the solvent resistance or solubility in THF of these latexes, the epoxy groups of the former were lost more quickly than those of the latter. Thus miniemulsion preparation conditions strongly affect the properties of obtained latex.