The mesoscopic phase of block copolymers PAn-PEG-PAn in aqueous solution was investigated by dissipative particle dynamics (DPD) simulation.The effects of the molar fraction of PAn segment in the copolymers and its concentration on the copolymers’ self-assembling were discussed.The distribution of PEG and PAn segments on the surface of the spherical micelle of the copolymer was interesting but was difficult to observe by experiments.The authors focused on investigating the characteristics of the spherical micelle of the copolymers in a low concentration.There existed two novel core-shell spherical micelles separately with increasing molar fraction of the PAn segment.One was that the PAn segment made up the shell and the PEG segments the core; the other was that the PEG segments made up the shell and the PAn segments the core.A greater part of water was aggregated to form cylindrical and spherical micelles

while the remaining was distributed in the block copolymers symmetrically when the mass fraction of the copolymers was more than 66.7%.DPD simulation could be considered as an assistant for the experimental research and could provide useful information which is difficult to obtain by experiments.