In this paper, perylene nanoparticles were prepared with a membrane mixer, in which one liquid was added into another one through the micropores of ultrafiltration membrane to reduce the droplets sizes, and the particles size distribution were improved compared with the classical method. The different influences of the positive addition style (in which organic solution of compound was added into water) [Baba et al., Opt. Mater. 21 (1-3) (2003) 591] and the reverse addition style (in which water was added into organic solution) [Byeong-Kwan et al., J. Am. Chem. Soc. 124 (2002) 14410] on the particles formation and morphology were investigated. The effects of permeation fluxes, as well as the fluorescence spectra, were also studied. (C) 2004 Published by Elsevier B.V.